query: where does fertilization take place in the femal reproductive system

pos: Female reproductive system ova (egg cells). The external sex organs are also known as the "genitals" and these are the organs of the vulva including the labia, clitoris, and vaginal opening. The vagina is connected to the uterus at the cervix. At certain intervals, the ovaries release an ovum, which passes through the Fallopian tube into the uterus. If, in this transit, it meets with sperm, a single sperm can enter and merge with the egg, fertilizing it. Fertilization usually occurs in the Fallopian tubes and marks the beginning of embryogenesis. The zygote will then divide over enough generations of cells to form

pos: Human reproductive system Human reproductive system The human reproductive system usually involves internal fertilization by sexual intercourse. In this process, the male inserts his penis into the female's vagina and ejaculates semen, which contains sperm. A small proportion of the sperm pass through the cervix into the uterus, and then into the Fallopian tubes for fertilization of the ovum. Only one sperm is required to fertilize the ovum. Upon successful fertilization, the fertilized ovum, or zygote, travels out of the Fallopian tube and into the uterus, where it implants in the uterine wall. This marks the beginning of gestation, better known as pregnancy,

pos: Female reproductive system uterus, Fallopian tubes, and ovaries. The vagina is a fibromuscular (made up of fibrous and muscular tissue) canal leading from the outside of the body to the cervix of the uterus or womb. It is also referred to as the birth canal in the context of pregnancy. The vagina accommodates the male penis during sexual intercourse. Semen containing spermatozoa is ejaculated from the male at orgasm, into the vagina potentially enabling fertilization of the egg cell (ovum) to take place. The cervix is the neck of the uterus, the lower, narrow portion where it joins with the upper part of

pos: Human reproductive system Examples of unclassifiable disorders are Peyronie's disease in males and endometriosis in females. Many congenital conditions cause reproductive abnormalities, but are better known for their other symptoms. These include: Turner syndrome, Klinefelter's syndrome, Cystic fibrosis, and Bloom syndrome. Human reproductive system The human reproductive system usually involves internal fertilization by sexual intercourse. In this process, the male inserts his penis into the female's vagina and ejaculates semen, which contains sperm. A small proportion of the sperm pass through the cervix into the uterus, and then into the Fallopian tubes for fertilization of the ovum. Only one sperm is required to

pos: Reproductive system sometimes to a unique pore such as a vagina or intromittent organ. The human reproductive system usually involves internal fertilization by sexual intercourse. During this process, the male inserts his erect penis into the female's vagina and ejaculates semen, which contains sperm. The sperm then travels through the vagina and cervix into the uterus or fallopian tubes for fertilization of the ovum. Upon successful fertilization and implantation, gestation of the fetus then occurs within the female's uterus for approximately nine months, this process is known as pregnancy in humans. Gestation ends with birth, the process of birth is known as

pos: Female reproductive system sperm. During fertilization the egg cell plays a role; it releases certain molecules that are essential to guiding the sperm and allows the surface of the egg to attach to the sperm's surface. The egg can then absorb the sperm and fertilization can then begin. The Fallopian tubes are lined with small hairs (cilia) to help the egg cell travel. The reproductive tract (or genital tract) is the lumen that starts as a single pathway through the vagina, splitting up into two lumens in the uterus, both of which continue through the Fallopian tubes, and ending at the distal ostia

pos: Gamete intrafallopian transfer moral theologians are nevertheless concerned with it because they "consider this to be a replacement of the marital act, and therefore immoral." Gamete intrafallopian transfer Gamete intrafallopian transfer (GIFT) is a tool of assisted reproductive technology against infertility. Eggs are removed from a woman's ovaries, and placed in one of the Fallopian tubes, along with the man's sperm. The technique, first attempted by Steptoe and Edwards and later pioneered by endocrinologist Ricardo Asch, allows fertilization to take place inside the woman's uterus. With the advances in IVF the GIFT procedure is used less as pregnancy rates in IVF tend to

pos: Gamete intrafallopian transfer Gamete intrafallopian transfer Gamete intrafallopian transfer (GIFT) is a tool of assisted reproductive technology against infertility. Eggs are removed from a woman's ovaries, and placed in one of the Fallopian tubes, along with the man's sperm. The technique, first attempted by Steptoe and Edwards and later pioneered by endocrinologist Ricardo Asch, allows fertilization to take place inside the woman's uterus. With the advances in IVF the GIFT procedure is used less as pregnancy rates in IVF tend to be equal or better and do not require laparoscopy when the egg is put back. It takes, on average, four to six

neg: Cloning clones such as Dolly that are born from SCNT are not perfect copies of the donor of the nucleus. Organism cloning (also called reproductive cloning) refers to the procedure of creating a new multicellular organism, genetically identical to another. In essence this form of cloning is an asexual method of reproduction, where fertilization or inter-gamete contact does not take place. Asexual reproduction is a naturally occurring phenomenon in many species, including most plants and some insects. Scientists have made some major achievements with cloning, including the asexual reproduction of sheep and cows. There is a lot of ethical debate over

neg: Reproductive isolation of the pollen tubes may be detained at some point between the stigma and the ovules, in such a way that fertilization does not take place. This mechanism of reproductive isolation is common in the angiosperms and is called "cross-incompatibility" or "incongruence". A relationship exists between self-incompatibility and the phenomenon of cross-incompatibility. In general crosses between individuals of a self-compatible species (SC) with individuals of a self-incompatible (SI) species give hybrid offspring. On the other hand, a reciprocal cross (SI x SC) will not produce offspring, because the pollen tubes will not reach the ovules. This is known as "unilateral

neg: Reproductive system and deposit sperm. Humans have a high level of sexual differentiation. In addition to differences in nearly every reproductive organ, numerous differences typically occur in secondary sexual characteristics. The male reproductive system is a series of organs located outside of the body and around the pelvic region of a male that contribute towards the reproduction process. The primary direct function of the male reproductive system is to provide the male sperm for fertilization of the ovum. The major reproductive organs of the male can be grouped into three categories. The first category is sperm production and storage. Production takes place

neg: Hydrosalpinx becomes agglutinated, the resulting obstruction does not allow the tubal fluid to pass; it accumulates and reverts its flow downstream, into the uterus, or production is curtailed by damage to the endosalpinx. This tube then is unable to participate in the reproductive process: sperm cannot pass, the egg is not picked up, and fertilization does not take place. Other causes of distal tubal occlusion include adhesion formation from surgery, endometriosis, and cancer of the tube, ovary or other surrounding organs. A hematosalpinx is most commonly associated with an ectopic pregnancy. A pyosalpinx is typically seen in a more acute stage

neg: Reproductive system stimulates some of the ova to develop and grow. One ovum is released and it passes through the fallopian tube into the uterus. Hormones produced by the ovaries prepare the uterus to receive the ovum. It sita her and awaits the sperm for fertilization to occur. When this does not occur i.e. no sperm for fertilization, the lining of the uterus, called the endometrium, and unfertilized ova are shed each cycle through the process of menstruation. If the ovum is fertilized by sperm, it attaches to the endometrium and the fetus develops. Most mammal reproductive systems are similar, however, there

neg: Membranipora membranacea predators also reduces growth of a colony. Colonies of "M. membranacea" are protandrous sequential hermaphrodites, where colonies transition from male to female reproductive stages, allowing fertilization to occur between colonies or within colonies. Fertilization takes places in the coelomic fluid of female colonies, and the eggs are released through an opening in the lophophore known as the coelomophore. Reproduction or growth of the colony can also take place by budding in a radial pattern from the first established zooid, the ancestrula. "M. membranacea" prefers shallow marine habitats between the mid intertidal to the shallow sublittoral. It may also be found

neg: Reproductive system of gastropods of reproductive system in stylommatophorans is common feature. Such variability may include: also Examples of reproductive system of various land snails: The structure of the reproductive system is strictly hermaphroditic. From the gonads, a hermaphrodite duct, a duct which is designed to transport both sperm and eggs, leads to a portion of the reproductive tract where the duct splits into a strictly male and strictly female portion. The female portion includes a fertilization pouch and posterior and anterior mucus glands, which open up into a pallial cavity which leads to a small muscular vagina. The male portion of the reproductive

neg: Reproductive system of gastropods getting modified, the sperm passes into the penis. During mating season, the glandular cells in the penis sheath and prepuce swell to facilitate eversion of the penis. The sperm gets pushed through the penis, where they are introduced into the tail end of its copulatory partner. Within the partner snail, after fertilization from the foreign sperm, the eggs pass into the albumen gland where they are coated in mucus which forms the egg capsule. Eggs are released immediately before oviposition. Unlike in land gastropod species where fertilization occurs in fertilization pockets, fertilization in freshwater species happens at the lower end

neg: Insect reproductive system Ephemeroptera. Ovipositors take two forms: Insect reproductive system Most insects reproduce oviparously, i.e. by laying eggs. The eggs are produced by the female in a pair of ovaries. Sperm, produced by the male in one testis or more commonly two, is transmitted to the female during mating by means of external genitalia. The sperm is stored within the female in one or more spermathecae. At the time of fertilization, the eggs travel along oviducts to be fertilized by the sperm and are then expelled from the body ("laid"), in most cases via an ovipositor. Female insects are able to make

neg: Reproductive system of gastropods via the penis and enters the females gonopore. Additional reproductive structures include Females have a gonopore that is connected to a seminal receptacle. The gonopore acts as an opening through which eggs are deposited. The opening leads into the mantle tubule, in which eggs flow from the oviduct and ovary. The mantle tubule produces three things, yolk; carries most of the nutrients needed to develop a healthy offspring, egg capsule formation, and sperm reception and storage; where fertilization occurs. After fertilization, eggs travel to the albumin glands to fill the yolk with protein, and lastly, the egg travels through the

neg: Embryophyte features related to their reproductive cycles which distinguish them from all other plant lineages. Firstly, their gametophytes produce sperm and eggs in multicellular structures (called 'antheridia' and 'archegonia'), and fertilization of the ovum takes place within the archegonium rather than in the external environment. Secondly, and most importantly, the initial stage of development of the fertilized egg (the zygote) into a diploid multicellular sporophyte, take place within the archegonium where it is both protected and provided with nutrition. This second feature is the origin of the term 'embryophyte' – the fertilized egg develops into a protected embryo, rather than dispersing

neg: Heterospory of both fossil and surviving plants. The retention of megaspores and the dispersal of microspores allow for both dispersal and establishment reproductive strategies. This adaptive ability of heterospory increases reproductive success as any type of environment favors having these two strategies. Heterospory stops self-fertilization from occurring in a gametophyte, but does not stop two gametophytes that originated from the same sporophyte from mating. This specific type of self-fertilization is termed as sporophytic selfing, and it occurs most commonly among angiosperms. While heterospory stops extreme inbreeding from occurring, it does not prevent inbreeding altogether as sporophytic selfing can still occur. A

neg: Reproductive biology together in order to produce offspring. The female reproductive system includes the structures involved in ovulation, fertilization, development of an embryo, and birth. These structures include: Estrogen is one of the sexual reproductive hormones that aid in the sexual reproductive system of the female. The male reproductive system includes sex accessory glands, sex accessory ducts, testes, and external genitalia. Testosterone, although present in both males and females, is relatively more abundant in males. Testosterone serves as one of the sexual reproductive hormones in the male reproductive system. Animal reproduction occurs by two modes of action, including both sexual and asexual

neg: Religious response to assisted reproductive technology and artificial contraception since they separate the procreative goal of marital sex from the goal of uniting married couples. The Roman Catholic Church permits the use of a small number of reproductive technologies and contraceptive methods like natural family planning, which involves charting ovulation times. The church allows other forms of reproductive technologies that allow conception to take place from normative sexual intercourse, such as a fertility lubricant. Pope Benedict XVI has publicly re-emphasized the Catholic Church's opposition to in vitro fertilization (IVF), claiming it replaces love between a husband and wife. In addition, the church opposes IVF because it

neg: Human reproductive system until birth. The male reproductive system has one function: to produce and deposit sperm. Humans have a high level of sexual differentiation. In addition to differences in nearly every reproductive organ, there are numerous differences in typical secondary sex characteristics. The male reproductive system is a series of organs located outside the body and around the pelvis region of a male that contribute towards the reproduction process. The primary direct function of the male reproductive system is to provide the male sperm for fertilization of the ovum. The major reproductive organs of the male can be grouped into three categories.

neg: Reproductive system while male snakes and lizards each possess a pair of penis-like organs. Most amphibians exhibit external fertilization of eggs, typically within the water, though some amphibians such as caecilians have internal fertilization. All have paired, internal gonads, connected by ducts to the cloaca. Fish exhibit a wide range of different reproductive strategies. Most fish, however, are oviparous and exhibit external fertilization. In this process, females use their cloaca to release large quantities of their gametes, called spawn into the water and one or more males release "milt", a white fluid containing many sperm over the unfertilized eggs. Other species of

neg: Male reproductive system male reproductive system is the process whereby the reproductive organs grow, mature and are established. It begins with a single fertilized egg and culminates 38 weeks later with birth of a male child. It is a part of the stages of sexual differentiation. The development of the male reproductive system coincides with the urinary system. The development of them can also be described together as the development of the urinary and reproductive organs. Sexual identity is determined at fertilization when the genetic sex of the zygote has been initialized by a sperm cell containing either an X or Y chromosome.

neg: Eucestoda a duct system to the oviduct, where, in a modified region, the ovum is enclosed in a shell with yolk cells. After the gonads and their ducts have finished maturing, the female reproductive organs begin to mature. The oviduct develops a vagina and enlarges into the uterus, where fertilization and embryonic development occur. Egg formation is a result of copulation. A proglottid can copulate with itself, with other proglottids in the same worm, or with proglottids in other worms, and hypodermic fertilization sometimes occurs. When a gravid proglottid that is distended with an embryo reaches the end of the strobila,

neg: Land snail air breathing land snails perform courtship behaviors before mating. The courtship may last anywhere between two and twelve hours. In a number of different families of land snails and slugs, prior to mating one or more love darts are fired into the body of the partner. Prolific breeders, pulmonate land snails inseminate each other in pairs to internally fertilize their ova via a reproductive opening on one side of the body, near the front, through which the outer reproductive organs are extruded so that exchange of sperm can take place. Fertilization then occurs and the eggs develop. Each brood may

neg: Responsible Parenthood and Reproductive Health Act of 2012 and counseled in a humane, non-judgmental and compassionate manner". It also states that "abortion remains a crime and is punishable", as the Constitution declares that “the State shall equally protect the life of the mother and the life of the unborn from conception”. The position of the Philippine Medical Association (PMA) "is founded strongly on the principle that 'life or conception begins at fertilization' at that moment where there is fusion or union of the sperm and the egg and thus a human person or human being already does exist at the moment of fertilization". The PMA condemns abortifacients that

neg: Chelicerata living arachnids use internal fertilization, which is direct in some species, in other words the males' genitalia make contact with the females'. However, in most species fertilization is indirect. Male spiders use their pedipalps as syringes to "inject" sperm into the females' reproductive openings, but most arachnids produce spermatophores (packages of sperm) which the females take into their bodies. Courtship rituals are common, especially in the most powerful predators, where males risk being eaten before mating. Most arachnids lay eggs, but all scorpions and a few mites keep the eggs inside their bodies until they hatch and offspring rather like

neg: Internal fertilization molluscs undertake internal fertilization by transferring a spermatophore, a bundle of sperm, from the male to the female. Following fertilization, the embryos are laid as eggs in oviparous organisms, or in viviparous organisms, continue to develop inside the reproductive tract of the mother to be born later as live young. In some animals like in sponges fertilization is internal Fertilization which takes place inside the female body is called internal fertilization in animals is done through the following different ways: At some point, the growing egg or offspring must be expelled. There are several possible modes of reproduction. These are

neg: Raillietina tetragona in comparison to other species are oval scolex and suckers, with relatively elongated neck. "R. tetragona" is strictly hermaphroditic having a complete reproductive system in itself. Each mature proglottid has a set of male and female reproductive organ and genital pores on one side. Testes are located on both sides of the ovary and behind vitellarium. Each egg capsule contained 4-12 eggs and many calcareous corpuscles, each of which is surrounded by a membrane. The male reproductive system matures first. As the two reproductive systems matured, the proglottids became gravid after fertilization. The tapeworm completes its life cycle in two

neg: Mating of gastropods the female reproductive system for storage (in the spermatheca) and later fertilisation. Intromission is simultaneously reciprocal in some species such as "Ariolimax dolichophallus" and unilateral in others such as "Ariolimax californicus" After sperm transfer a process termed apophallation, or penis amputation, may take place. This is a lengthy process whereby the penis of one or both slugs is chewed off using the radula. In the case where one penis is chewed off, this is usually done by the other slug. A replacement penis does not grow back. Apophallation is most widely found in "Ariolimax" species, which have internal sperm exchange.

neg: Reproductive system fish are oviparous and have internal fertilization aided by pelvic or anal fins that are modified into an intromittent organ analogous to the human penis. A small portion of fish species are either viviparous or ovoviviparous, and are collectively known as livebearers. Fish gonads are typically pairs of either ovaries or testes. Most fish are sexually dimorphic but some species are hermaphroditic or unisexual. Invertebrates have an extremely diverse array of reproductive systems, the only commonality may be that they all lay eggs. Also, aside from cephalopods and arthropods, nearly all other invertebrates are hermaphroditic and exhibit external fertilization. All

neg: Pinophyta The cycles refers to the completion of female strobilus development from initiation to seed maturation. All three types or reproductive cycles have a long gap in between pollination and fertilization. One year reproductive cycle:The genera includes "Abies", "Picea", "Cedrus", "Pseudotsuga," "Tsuga", "Keteleeria" "(Pinaceae)" and "Cupressus, Thuja, Cryptomeria, Cunninghamia" and "Sequoia (Cupressaceae)". Female strobili are initiated in late summer or fall in a year, then they overwinter. Female strobili emerge followed by pollination in the following spring . Fertilization takes place in summer of the following year, only 3–4 months after pollination. Cones mature and seeds are then shed by the

neg: Poeciliidae oocyte with all the resources it needs prior to fertilization, so the egg is independent of the mother), but others are matrotrophic (literally "mother feeding": the mother provides the majority of resources to the developing offspring after fertilization). Members of the genus "Poeciliopsis", for example, show variable reproductive life history adaptations. "Poeciliopsis monacha", "P. lucida", and "P. prolifica" form part of the same clade within that genus. However, their modes of maternal provisioning vary greatly. "P. monacha" can be considered to be lecithotrophic because it does not really provide any resources for its offspring after fertilization - the pregnant female

neg: Reproductive system of gastropods form of sexual selection. Gastropods are defined as snails and slugs, belonging to a larger group called Molluscs. Gastropods have unique reproductive systems, varying significantly from one taxonomic group to another. They can be separated into three categories: marine, freshwater, and land. Reproducing in marine or freshwater environments makes getting sperm to egg much easier for gastropods, while on land it is much more difficult to get sperm to egg. The majority of gastropods have internal fertilization, but there are some prosobranch species that have external fertilization. Gastropods are capable of being either male or female, or hermaphrodites, and this

neg: Fish reproduction an internal organ unite inside the fish's body. In nature, this mode of reproduction can yield highly homozygous lines composed of individuals so genetically uniform as to be, in effect, identical to one another. The capacity for selfing in these fishes has apparently persisted for at least several hundred thousand years. Although inbreeding, especially in the extreme form of self-fertilization, is ordinarily regarded as detrimental because it leads to expression of deleterious recessive alleles, self-fertilization does provide the benefit of "fertilization assurance" (reproductive assurance) at each generation. Sexual parasitism is a mode of sexual reproduction, unique to anglerfish, in which

neg: Mangrove rivulus selfing in these fishes has apparently persisted for at least several hundred thousand years. Meioses that lead to self-fertilization can reduce genetic fitness by causing inbreeding depression. However, self-fertilization does provide the benefit of “fertilization assurance” (reproductive assurance) at each generation. Meiosis can also provide the adaptive benefit of efficient recombinational repair of DNA damages during formation of germ cells at each generation. This benefit may have prevented the evolutionary replacement of meiosis and selfing by a simpler type of clonal reproduction such as ameiotic or apomictic parthenogenesis. Adults may cannibalize juveniles, but only unrelated offspring. Overall the mangrove rivulus

neg: Silver–Russell syndrome syndrome, Angelman syndrome, and Beckwith–Wiedemann syndrome), Silver–Russell syndrome may be associated with the use of assisted reproductive technologies such as in vitro fertilization. For many years the diagnosis of Silver-Russell Syndrome was clinical. However, this lead to overlaps with syndromes with similar clinical features such as Temple Syndrome and 12q14 microdeletion syndrome. In 2017, an international consensus was published - detailing the steps clinicians should take to diagnose Silver-Russell Syndrome. It is now recommended to test for 11p15 loss of methylation and mUPD7 first. If they are negative, then testing for mUPD16, mUPD20 should take place. Testing for 14q32 should

neg: Leatherback sea turtle the Atlantic, females tagged in French Guiana have been recaptured on the other side of the ocean in Morocco and Spain. Mating takes place at sea. Males never leave the water once they enter it, unlike females, which nest on land. After encountering a female (which possibly exudes a pheromone to signal her reproductive status), the male uses head movements, nuzzling, biting, or flipper movements to determine her receptiveness. Males can mate every year but the females mate every two to three years. Fertilization is internal, and multiple males usually mate with a single female. This polyandry does not provide

neg: Paramesonephric duct The two are conjoined at the sinus tubercle. Paramesonephric ducts are present on the embryo of both sexes. Only in females do they develop into reproductive organs. They degenerate in males of certain species, but the adjoining mesonephric ducts develop into male reproductive organs. The sex based differences in the contributions of the paramesonephric ducts to reproductive organs is based on the presence, and degree of presence, of Müllerian inhibiting factor. During the formation of the reproductive system, the paramesonephric ducts are formed just lateral to the mesonephric ducts in both female and male embryos 6 weeks after fertilization. During

neg: Human reproductive system gametogenesis. This occurs when certain types of germ cells undergo meiosis to split the normal diploid number of chromosomes (n=46) into haploid cells containing only 23 chromosomes. In females, gametogenesis is known as oogenesis; this occurs in the ovarian follicles of the ovaries. This process does not produce mature ovum until puberty. In contrast with males, each of the original diploid germ cells or primary oocytes will form only one mature ovum, and three polar bodies which are not capable of fertilization. It has long been understood that in females, unlike males, all of the primary oocytes ever found in

neg: Cryptasterina hystera zone. "Cryptasterina hystera" is a hermaphrodite; the gonads can produce both sperm and eggs and are known as ovotestes. Fertilization of the eggs take place when sperm liberated by another starfish is drawn into the gonad through the gonoduct. The eggs are few in number and have large yolks and are retained inside the starfish which is viviparous. The brachiolaria larvae that develop inside the gonads "swim" in the fluid there and are eventually released into the sea through the gonopore as juvenile starfish. Members of the family Asterinidae appear prone to rapid change in their reproductive life cycle and

neg: Female reproductive system that open into the abdominal cavity. In the absence of fertilization, the ovum will eventually traverse the entire reproductive tract from the fallopian tube until exiting the vagina through menstruation. The reproductive tract can be used for various transluminal procedures such as fertiloscopy, intrauterine insemination, and transluminal sterilization. Chromosome characteristics determine the genetic sex of a fetus at conception. This is specifically based on the 23rd pair of chromosomes that is inherited. Since the mother's egg contains an X chromosome and the father's sperm contains either an X or Y chromosome, it is the male who determines the fetus's sex.

neg: Insect reproductive system Insect reproductive system Most insects reproduce oviparously, i.e. by laying eggs. The eggs are produced by the female in a pair of ovaries. Sperm, produced by the male in one testis or more commonly two, is transmitted to the female during mating by means of external genitalia. The sperm is stored within the female in one or more spermathecae. At the time of fertilization, the eggs travel along oviducts to be fertilized by the sperm and are then expelled from the body ("laid"), in most cases via an ovipositor. Female insects are able to make eggs, receive and store sperm,

neg: Reproductive isolation incompatibility", which also occurs when two SC or two SI species are crossed. A number of mechanisms which act after fertilization preventing successful inter-population crossing are discussed below. A type of incompatibility that is found as often in plants as in animals occurs when the egg or ovule is fertilized but the zygote does not develop, or it develops and the resulting individual has a reduced viability. This is the case for crosses between species of the frog genus, where widely differing results are observed depending of the species involved. In some crosses there is no segmentation of the zygote

neg: Insect reproductive system substances for sperm maintenance, transport, and fertilization, as well as for protection of eggs. They can produce glue and protective substances for coating eggs or tough coverings for a batch of eggs called oothecae. Spermathecae are tubes or sacs in which sperm can be stored between the time of mating and the time an egg is fertilized. Paternity testing of insects has revealed that some, and probably many, female insects use the spermatheca and various ducts to control or bias sperm used in favor of some males over others. The main component of the male reproductive system is the testis,

neg: Reproductive system of gastropods sperm. Gametes form in the ovotesties, an organ which produces both ova and sperm, and pass down into the hermaphroditic duct to the albumen gland, the junction of where the common duct splits to either vas deferens or oviduct, where they are stored until they are needed for either mating or self-fertilization. It is believed that this junction acts as a regulatory mechanism via contracting muscles, to help direct sperm or eggs into the correct ducts. The sperm passes into the male duct, or vas deferens, where is receives secretory additions in the form of mucus from the prostate. After

neg: Male reproductive system during puberty causes the male secondary sexual characteristics to be manifested. the manifestation of secondary sexual characteristics include the growth of: Secondary development includes the increased activity of the eccrine sweat glands and sebaceous glands along with the darkening of the skin in the scrotal region. Chromosomal abnormalities can occur during fertilization impacting the development of the male reproductive system. The genotype of the male consists of a Y chromosome paired with an X chromosome. Female gender is determined by the absence of a Y chromosome. Some individuals are male who have the XX male syndrome and androgen insensitivity syndrome.

neg: Anorchia despite lacking the necessary masculinizing hormones during prenatal, childhood, and adolescent development. Anorchic individuals who have a female identity may be administered estrogen alone in place of testosterone as no androgen blockers are necessary due to the lack of gonads. Other names for anorchia include Anorchia Anorchia (also called anorchidism or anorchism) is a disorder of sex development in which a person with XY karyotype, which usually corresponds to male sex, is born without testes. Within a few weeks of fertilization, the embryo develops rudimentary gonads (testes), which produce hormones responsible for the development of the reproductive system. If the

neg: Pedro Beauchamp scientific works in myriad medical journals, and has been an invited speaker to numerous medical conferences. Dr. Beauchamp is a member of the American Society of Reproductive Medicine and a co-founder of "SART," the Society of Assisted Reproductive Techniques and Reproductive Endocrinology and In-fertilization Society. In 1987, Dr. Beauchamp was awarded a "Guanín" award. He was also awarded the "DoctorˆÉ¬çs Choice Award" from the Buena Vista magazine. Pedro Beauchamp Dr. Pedro Beauchamp is an endocrinologist who is the first Puerto Rican specialist certified by the American Reproductive Endocrinology and Infertility Board. In 1985, he performed the first in vitro fertilization

neg: Reproductive compensation level of recessive genetic disorders in a population. According to Andrew Overall of the University of Edinburgh, “Reproductive compensation may be particularly significant where economic or social factors mean that families are small compared to the maximum reproductive rate. Within small families, diseased infants may be more likely to be replaced. As a consequence, parents with otherwise reduced fertility have a greater influence on the frequency of recessive alleles in future generations.” Ian Hastings has argued that reproductive technologies such as embryo sex selection, preimplantation genetic diagnosis with in vitro fertilization, and selective termination of pregnancy may increase the frequency

neg: Sexual selection in insects be choosier than females. As an offering, males are capable of providing nuptial gifts secretions, which can be more expensive than female reproductive investment, parental care, where the reproductive costs in males are higher than in females because they invest large quantities of resources and time after egg fertilization, and foraging and nesting sites to the females. Moreover, these factors decrease their subsequent male reproductive opportunities, and the availability of males. An example of male parental care can be found in belostomatid water bugs, where the male, after fertilizing the eggs, allows the female to glue her eggs onto his

neg: Beginning of human personhood referred to as fertilization. For fertilization to take place and a baby to begin growing, the sperm cell must come in direct contact with the egg cell." Similarly, a textbook used in Evanston, Illinois stated: "Life begins when a sperm cell and an ovum (egg cell) unite." Catholic philosopher Peter Kreeft goes so far as to say: Well, every biology textbook in the world, before "Roe v. Wade", was not in doubt in answering the question, "When does an individual life of any mammalian species begin?" The answer is, "When the genetic code is complete." When instead of the haploid

neg: Mate desertion mating opportunities are higher in males than in females. Because males have greater variance in reproductive success, their lifetime reproductive success depends more on number of mating opportunities, and thus they often benefit more from desertion. Second, mode of fertilization often influences degree of parental care, which in turn influences which sex will desert. Generally speaking, male parental care is predicted by external fertilization, and female parental care is predicted by internal fertilization. This pattern of parental care is best explained by the “Association Hypothesis," which argues that association with embryos predisposes a sex for parental care. For example, in

neg: Preimplantation genetic diagnosis will reinforce societal prejudice.<ref name="doi10.1089/073003103322616742"></ref> The preimplantation genetic diagnosis is allowed in Ukraine and from November 1, 2013 is regulated by the order of the Ministry of health of Ukraine "On approval of the application of assisted reproductive technologies in Ukraine" from 09.09.2013 № 787. . In the UK, assisted reproductive technologies are regulated under the Human Fertilization and Embryology Act (HFE) of 2008. However, the HFE Act does not address issues surrounding PGD. Thus, the HFE Authority (HFEA) was created in 2003 to act as a national regulatory agency which issues licenses and monitors clinics providing PGD. The HFEA

neg: Reproductive isolation interspecific pollen. This demonstrates how a specific point in the reproductive process is manipulated by a particular isolating mechanism to prevent hybrids. Another well-documented example of a pre-fertilization isolating mechanism in plants comes from study of the 2 wind-pollinated birch species. Study of these species led to the discovery that mixed conspecific and interspecific pollen loads still result in 98% conspecific fertilization rates, highlighting the effectiveness of such barriers. In this example, pollen tube incompatibility and slower generative mitosis have been implicated in the post-pollination isolation mechanism. Crosses between diploid and tetraploid species of Paspalum provide evidence of a post-fertilization

neg: Spermiogenesis sperm from fertilizing the egg prior to traveling through the male and female reproductive tracts. Capacitation of the sperm by the enzymes FPP (fertilization promoting peptide, produced in the epididymis) and heparin (in the female reproductive tract) removes this coat and allows sperm to bind to the egg. Spermiogenesis Spermiogenesis is the final stage of spermatogenesis, which sees the maturation of spermatids into mature, motile spermatozoa. The spermatid is a more or less circular cell containing a nucleus, Golgi apparatus, centriole and mitochondria. All these components take part in forming the spermatozoon. The process of spermiogenesis is traditionally divided into

neg: Responsible Parenthood and Reproductive Health Act of 2012 "destroys the fertilized egg or the embryo" and "abhors any procedure...or medication that will interrupt any stage of fertilization and prevents its normal, physiological, uninterrupted growth to adulthood". Jo Imbong, founder of the Abay Pamilya Foundation, reported that "Lagman said in a House hearing that the bill would protect human life 'from implantation' ", and not from fertilization, noting at the same time that the Records of the Constitutional Commission state that “Human life begins at fertilization”. Proponents argue that research by the Guttmacher Institute, involved in advancing international reproductive health, reveals that the use of contraceptives can reduce abortion

neg: Portuguese dogfish reproductively active at a time. However, previous accounts have described continuous reproduction with females in various stages of pregnancy present year-round. The ovarian follicles take some time to mature; they are ovulated into the uterus at a diameter of . Studies of females have found no traces of sperm inside their reproductive tracts, which suggests that fertilization occurs immediately following copulation, which may also trigger ovulation. The reproductive cycles of Portuguese dogfish in the Atlantic and Pacific are generally similar; sharks off Japan tend to produce larger numbers of smaller oocytes than elsewhere, while sharks off the British Isles exhibit

neg: Mollusca complex variations. All produce eggs, from which may emerge trochophore larvae, more complex veliger larvae, or miniature adults. Two gonads sit next to the coelom, a small cavity that surrounds the heart, into which they shed ova or sperm. The nephridia extract the gametes from the coelom and emit them into the mantle cavity. Molluscs that use such a system remain of one sex all their lives and rely on external fertilization. Some molluscs use internal fertilization and/or are hermaphrodites, functioning as both sexes; both of these methods require more complex reproductive systems. The most basic molluscan larva is a

neg: Selection methods in plant breeding based on mode of reproduction families. Asexual reproduction covers all those modes of multiplication of plants where normal gamete formation and fertilization does not take place making these distinctly different from normal seed production crops. In the absence of sexual reproduction, the genetic composition of plant material being multiplied remains essentially the same as its source plant. Clones of mother plants can be made with the exact genetic composition of the mother plant. Superior plants are selected and propagated vegetatively; the vegetative propagated offspring are used to develop stable varieties without any deterioration due to segregation of gene combinations. This unique characteristic of asexual reproduction

neg: Parthenogenesis in amphibians Parthenogenesis in amphibians Parthenogenesis is a form of reproduction where eggs develop without fertilization, resulting in unisexual species. This phenomenon is closely related with reproductive modes such as hybridogenesis, where fertilization occurs, but the paternal DNA is not passed on. Among amphibians, it is seen in numerous frog and salamander species, but has not been recorded in caecilians. Haploid parthenogenesis has been achieved experimentally in amphibians, through approaches that could be considered artificial gynogenesis. Oscar Hertwig first achieved artificial parthenogenesis in frogs in 1911, using eggs fertilized by irradiated sperm. The radiation destroyed the DNA within the sperm, but nearly

neg: Infertility a laboratory setting, with the intent of producing one or more embryos. Fertilization takes place outside the body, and the fertilized egg is reinserted into the woman's reproductive tract, in a procedure called embryo transfer. Other medical techniques are e.g. tuboplasty, assisted hatching, and Preimplantation genetic diagnosis. IVF is the most commonly used ART. It has been proven useful in overcoming infertility conditions, such as blocked or damaged tubes, endometriosis, repeated IUI failure, unexplained infertility, poor ovarian reserve, poor or even nil sperm count. ICSI technique is used in case of poor semen quality, low sperm count or failed fertilization

neg: Reproductive system the female. In species where the hectocotylus is missing, the "penis" is long and able to extend beyond the mantle cavity and transfer the spermatophores directly to the female. Most insects reproduce oviparously, i.e. by laying eggs. The eggs are produced by the female in a pair of ovaries. Sperm, produced by the male in one testis or more commonly two, is transmitted to the female during mating by means of external genitalia. The sperm is stored within the female in one or more spermathecae. At the time of fertilization, the eggs travel along oviducts to be fertilized by the

neg: Human reproduction giving them 23 pairs. After a gestation period, typically for nine months, is followed by childbirth. The fertilization of the ovum may be achieved by artificial insemination methods, which do not involve sexual intercourse. The male reproductive system contains two main divisions: the testes where sperm are produced, and the penis. In humans, both of these organs are outside the abdominal cavity. Having the testes outside the abdomen facilitates temperature regulation of the sperm, which require specific temperatures to survive about 2-3 °C less than the normal body temperature i.e. 37 °C. In particular, the extraperitoneal location of the testes

neg: Yuma myotis time in torpor, but probably do not migrate any significant distance. The echolocation calls of Yuma myotis are frequency modulated and sweep abruptly from 59 to 72 kHz down to 45 to 50 kHz. Yuma myotis typically undergo a polygynandrous mating system, where a female pairs with several males, each of which also pairs with several different females. Males and females are usually around 1 year old at the time of sexual and reproductive maturity, and they will only produce 1 offspring. Mating occurs in the fall, but the females retain the sperm for several months, so ovulation and fertilization

neg: Echinoderm replacement is also observed. The robust larval growth is responsible for many echinoderms being used as popular model organisms in developmental biology. Echinoderms become sexually mature after approximately two to three years, depending on the species and the environmental conditions. They are nearly all gonochoric, though a few species are hermaphroditic. The eggs and sperm cells are typically released into open water, where fertilization takes place. The release of sperm and eggs is synchronised in some species, usually with regard to the lunar cycle. In other species, individuals may aggregate during the reproductive season, thereby increasing the likelihood of successful

neg: Semotilus atromaculatus then initiates building a spawning site to draw in females in the surrounding area. This most likely occurs in small pits with small pebbles to protect the area where eggs are laid. Once females enter, the male wraps around her pectoral fin and body, fertilization occurs, and the female leaves. Around 25-30 eggs are released each fertilization cycle. Often, these reproductive cycles occur in communal nesting sites, where the male controls the territory and protects it from intruders. During the breeding season, males grow small, keratin-based bumps, called tubercles, on their head, which are used in ritualized combat. This hardly

neg: Parental care in birds effort reserved for reproduction is diminished by a need to maintain the immune system this leads to a physiological condition hindering breeding. (Sheldon & Verhulst, 1996; Norris & Evans, 2000) In most bird species, females invest in parental care more than males at the expense of reproductive success. If both parents contribute to young feeding and guarding at the same rate, the parents reproductive success increases while together. Desertion by any mate would be a setback because parental investment would be diverted to finding a new mate. A male often deserts first because internal fertilization allows the male to impregnate

neg: Reproductive system to develop after it leaves the female's body. Unlike most vertebrates female birds typically have only one functional ovary and oviduct. As a group, birds, like mammals, are noted for their high level of parental care. Reptiles are almost all sexually dimorphic, and exhibit internal fertilization through the cloaca. Some reptiles lay eggs while others are viviparous (animals that deliver live young). Reproductive organs are found within the cloaca of reptiles. Most male reptiles have copulatory organs, which are usually retracted or inverted and stored inside the body. In turtles and crocodilians, the male has a single median penis-like organ,

neg: External fertilization species release gametes during this time. In some cases, fertilization can take place on a spawning animal’s surface and when the animals are in the turbulent wake. Although fertilization is usually thought of as a short-term process, there is the possibility of gametes being retained on the surface of an animal for an extended period of time. In order to release an egg or sperm over time, clumps are formed that float in the water column. This allows for a variation in locations and time differences of fertilization taking place by the same invertebrate. The earliest amphibians were all internal

neg: GroES whether pregnancy prevention mechanism of birth control methods act before or after fertilization. A 1982 study evaluating EPF levels in women with IUDs concluded that post-fertilization mechanisms contribute significantly to the effectiveness of these devices. However, more recent evidence, such as tubal flushing studies indicates that IUDs work by inhibiting fertilization, acting earlier in the reproductive process than previously thought. For groups that define pregnancy as beginning with fertilization, birth control methods that have postfertilization mechanisms are regarded as abortifacient. There is currently contention over whether hormonal contraception methods have post-fertilization methods, specifically the most popular hormonal method - the

neg: Immunocontraception it as a possible immunocontraceptive vector. In placental mammals, fertilization typically occurs inside the female in the oviducts. The oviducts are positioned near the ovaries where ova are produced. An ovum therefore needs only to travel a short distance to the oviducts for fertilization. In contrast sperm cells must be highly motile, since they are deposited into the female reproductive tract during sexual intercourse and must travel through the cervix (in some species) as well as the uterus and the oviduct (in all species) to reach an ovum. Sperm cells that are motile are spermatozoa. Spermatozoa are protected from the

neg: Sexual reproduction the motile sperm are splashed away from the antheridia, which are normally produced on the top side of the thallus, and swim in the film of water to the archegonia where they fertilize the egg. To promote out crossing or cross fertilization the sperm are released before the eggs are receptive of the sperm, making it more likely that the sperm will fertilize the eggs of different thallus. A zygote is formed after fertilization, which grows into a new sporophytic plant. The condition of having separate sporephyte and gametophyte plants is called alternation of generations. Other plants with similar reproductive

neg: Reproductive technology Reproductive technology Reproductive technology encompasses all current and anticipated uses of technology in human and animal reproduction, including assisted reproductive technology, contraception and others. Assisted reproductive technology (ART) is the use of reproductive technology to treat low fertility or infertility. ART is currently the only form of reproductive technology in clinical use, and is more effective in those suffering from ovulatory disorders or endometriosis (those without a functional uterus, for example, for the time being can only conceive through surrogacy methods). Examples of ART include "in vitro" fertilization and its possible expansions, including: Reproductive technology can inform family planning by

neg: Monocotyledon reproduction and competition. These strategies either promote fertilization with self and suppress fertilization with others resulting in self-pollination, or they suppress fertilization with self and promote fertilization with others resulting in cross-pollination. Strategies also exist to suppress fertilization with other species as reproductive barriers. Pollination strategies have the same function as breeding systems, however they occur at the ecological level or at the level of floral structure rather than at the molecular level on the stigma through genetic recognition Self-pollination can be prevented by both physical and temporal mechanisms that have evolved in response to the interactions with pollen vectors; these

neg: Pregnancy Pregnancy Pregnancy, also known as gestation, is the time during which one or more offspring develops inside a woman. A multiple pregnancy involves more than one offspring, such as with twins. Pregnancy can occur by sexual intercourse or assisted reproductive technology. Childbirth typically occurs around 40 weeks from the last menstrual period (LMP). This is just over nine months, where each month averages 31 days. When measured from fertilization it is about 38 weeks. An embryo is the developing offspring during the first eight weeks following fertilization, after which, the term "fetus" is used until birth. Symptoms of early pregnancy

neg: External fertilization enhance the chances of fertilization. The presence of food, resources, favorable environmental conditions, and the lack of predators are thought of when thinking of survival of the next generation. When the female is producing eggs, they perform predator satiation, which is when multiple females will release gametes in a mass reproductive event. The Great Barrier Reef is known for having a “mass spawn.” This occurs the week after the full moon in October. This mass reproductive event is given by reef forming corals, which perform a synchronized release of gametes in one evening from dusk to midnight. Up to 130

neg: Human reproduction Human reproduction Human reproduction is any form of sexual reproduction resulting in human fertilization, typically involving sexual intercourse between a man and a woman. During sexual intercourse, the interaction between the male and female reproductive systems results in fertilization of the woman's ovum by the man's sperm. These are specialized reproductive cells called gametes, created in a process called meiosis. While normal cells contains 46 chromosomes, 23 pairs, gamete cells only contain 23 chromosomes, and it is when these two cells merge into one zygote cell that genetic recombination occurs and the new zygote contains 23 chromosomes from each parent,

neg: Marine life (apart from bivalves) it has a rasping tongue called a radula used for feeding. Thirdly, it has a nervous system including a complex digestive system using microscopic, muscle-powered hairs called cilia to exude mucus. The generalized mollusc has two paired nerve cords (three in bivalves). The brain, in species that have one, encircles the esophagus. Most molluscs have eyes and all have sensors detecting chemicals, vibrations, and touch. The simplest type of molluscan reproductive system relies on external fertilization, but more complex variations occur. All produce eggs, from which may emerge trochophore larvae, more complex veliger larvae, or miniature adults.

neg: Semelparity and iteroparity care due to internal fertilization and incubation of offspring and nursing young after birth, which requires high maternal survival rate after fertilization and offspring weaning. Also, female mammals have relatively low reproductive rate compared to invertebrates or fish because they invest a lot of energy in maternal care. However, male reproductive rate is much less constrained in mammals because only females bear young. Males that die after one mating season can still produce a large number of offspring if he invests all of his energy in intense matings with many females. Scientists have hypothesized that natural selection has allowed semelparity

neg: Assisted reproductive technology body or donating them to another woman." According to CDC, "they do not include treatments in which only sperm are handled (i.e., intrauterine—or artificial—insemination) or procedures in which a woman takes medicine only to stimulate egg production without the intention of having eggs retrieved." In Europe, ART also excludes artificial insemination and includes only procedures where oocytes are handled. The WHO also defines ART this way. Most fertility medications are agents that stimulate the development of follicles in the ovary. Examples are gonadotropins and gonadotropin releasing hormone. In vitro fertilization is the technique of letting fertilization of the male and

neg: Reproductive isolation compatible, indicating that other factors also determine the form of these complicated structures. Mechanical isolation also occurs in plants and this is related to the adaptation and coevolution of each species in the attraction of a certain type of pollinator (where pollination is zoophilic) through a collection of morphophysiological characteristics of the flowers (called floral syndromes), in such a way that the transport of pollen to other species does not occur. The synchronous spawning of many species of coral in marine reefs means that inter-species hybridization can take place as the gametes of hundreds of individuals of tens of species

neg: Yonahlossee salamander at the interface between the log and the ground. They can also be found active on humid or rainy nights, even crossing roads in suitable habitat. Little is known about the reproductive habits of this species. Reproduction does take place terrestrially and eggs are deposited in underground cavities where, like other members of the genus, the female may guard the eggs until they hatch. Spermatogenesis most likely occurs after the emergence from hibernation. Courtship is assumed to occur in early August, as this is the time pairs of salamanders have been found under a single cover object and males have

neg: Copulation (zoology) Copulation (zoology) In zoology, copulation is animal sexual behavior in which a male introduces sperm into the female's body, especially directly into her reproductive tract. This is an aspect of mating. Many animals that live in water use external fertilization, whereas internal fertilization may have developed from a need to maintain gametes in a liquid medium in the Late Ordovician epoch. Internal fertilization with many vertebrates (such as reptiles, some fish, and most birds) occurs via cloacal copulation, known as cloacal kiss (see also hemipenis), while mammals copulate vaginally, and many basal vertebrates reproduce sexually with external fertilization. In non-primate

neg: Pinophyta end of that same year. Pollination and fertilization occurs in a single growing season. Two-year reproductive cycle:The genera includes "Widdringtonia", "Sequoiadendron" ("Cupressaceae") and most species of "Pinus". Female strobilus initials are formed in late summer or fall then overwinter. It emerges and receives pollen in the first year spring and become conelets. The conelet goes through another winter rest and in the spring of the 2nd year. The Archegonia form in the conelet and fertilization of the archegonia occurs by early summer of the 2nd year, so the pollination-fertilization interval exceeds a year. After fertilization, the conelet is considered an

neg: Human reproductive ecology reproductive capabilities. The key components of fecundity are a person's reproductive maturation and the maintenance of their reproductive system. In humans, the timing of female reproductive maturation is particularly variable and is heavily influenced by ecological considerations. In addition, the age at menarche has decreased over time in many global populations. This phenomenon is referred to as the secular trend. Age at menarche is one measure of the fecundity of an individual female. Male reproductive maturity is less subject to environmental and ecological factors, and does not follow the secular trend that female puberty does. In adults, fecundity is determined

neg: Double fertilization Double fertilization "Double fertilization" is a complex fertilization mechanism of flowering plants (angiosperms). This process involves the joining of a female gametophyte (megagametophyte, also called the embryo sac) with two male gametes (sperm). It begins when a pollen grain adheres to the stigma of the carpel, the female reproductive structure of a flower. The pollen grain then takes in moisture and begins to germinate, forming a pollen tube that extends down toward the ovary through the style. The tip of the pollen tube then enters the ovary and penetrates through the micropyle opening in the ovule. The pollen tube proceeds

neg: Pregnancy rates for sexual intercourse are highest during the menstrual cycle time from some 5 days before until 1 to 2 days after ovulation. Fertilization can also occur by assisted reproductive technology such as artificial insemination and in vitro fertilisation. Fertilization (conception) is sometimes used as the initiation of pregnancy, with the derived age being termed fertilization age. Fertilization usually occurs about two weeks before the "next" expected menstrual period. A third point in time is also considered by some people to be the true beginning of a pregnancy: This is time of implantation, when the future fetus attaches to the

neg: Gianpiero D. Palermo Gianpiero D. Palermo Gianpiero D. Palermo is the developer of the revolutionary procedure known as intracytoplasmic sperm injection (ICSI) in 1991, which is able to overcome male infertility in many cases. Since 1993, he has been the Director of Assisted Fertilization and Andrology at The Center for Reproductive Medicine and Infertility and has led the ICSI Program there. He is also Professor of reproductive medicine at Weill Cornell Medical College of Cornell University. He leads a team of researchers involved in molecular and genetic aspects of fertilization and male infertility, follow-up of ICSI babies, the development of new procedures to

neg: Gianpiero D. Palermo treat age-related female infertility, and harvesting and differentiation of embryonic stem cells. Gianpiero D. Palermo Gianpiero D. Palermo is the developer of the revolutionary procedure known as intracytoplasmic sperm injection (ICSI) in 1991, which is able to overcome male infertility in many cases. Since 1993, he has been the Director of Assisted Fertilization and Andrology at The Center for Reproductive Medicine and Infertility and has led the ICSI Program there. He is also Professor of reproductive medicine at Weill Cornell Medical College of Cornell University. He leads a team of researchers involved in molecular and genetic aspects of fertilization and

neg: Rita Bakshi Rita Bakshi Rita Bakshi is an Indian gynecologist and IVF specialist. She is based in New Delhi. She trained in multiple hospitals beginning in 1978, including Lady Hardinge Medical College, University of Delhi where she completed her MBBS. Bakshi completed her MD (Gynae & Obstetrics) at Safdarjung Hospital, New Delhi in 1997. She is trained in Assisted Reproductive Technology and "In Vitro" Fertilization from the Kolkata Institute of Reproductive Medicine under Dr. B.N. Chakravorty. She took advanced training in tubal microsurgery and a World Health Organization fellowship in Gynae Oncology at AIIMS Delhi. She holds a Diploma in ART from

neg: Bulimulus tenuissimus The columella is suboblique, sometimes nearly vertical. The aperture is oval, colored like the exterior, onehalf the shell's length. The peristome is simple, unexpanded, acute. The right margin is regularly arcuate. The columellar margin is reflexed above, nearly covering the perforation. The width of the shell is 9 mm. The height of the shell is 17 mm. The reproductive biology of this species was studied by Silva et al. (2008): These hermaphroditic snails are mating and cross-fertilization normally occurs. When snails are isolated then self-fertilization can occur, but with the lower reproductive success. Eggs are laid in clutches from one

neg: Diadectomorpha Whether this is due to an actual lack of tadpole stage or taphonomy (many diadectomorphs were upland creatures where tadpoles would have a poor probability of being fossilized) is uncertain. Alfred Romer indicated that the anamniote/amniote divide might not have been very sharp, leaving the question of the actual mode of reproduction of these large animals unanswered. Possible reproductive modes include full amphibian spawning with aquatic tadpoles, internal fertilization with or without ovoviviparity, aquatic eggs with direct development or some combination of these. The reproductive mode might also have varied within the group. Diadectomorpha Diadectomorpha are a clade of large

neg: Reproductive success three variables for kin selection take place. If the relative genetic relatedness of the helper with the offspring is closer and their benefit is greater than the cost of the helper, then kin selection will be most likely be favored. Even though kin selection does not benefit individuals who invest in relatives' offspring, it still highly increases the reproduction success of a population by ensuring genes are being passed down to the next generation. Some research has suggested that historically, women have had a far higher reproductive success rate than men. Dr. Baumeister has suggested that the modern human has

neg: Anatomy into horny scales which create a waterproof layer. Reptiles are unable to use their skin for respiration as do amphibians and have a more efficient respiratory system drawing air into their lungs by expanding their chest walls. The heart resembles that of the amphibian but there is a septum which more completely separates the oxygenated and deoxygenated bloodstreams. The reproductive system has evolved for internal fertilization, with a copulatory organ present in most species. The eggs are surrounded by amniotic membranes which prevents them from drying out and are laid on land, or develop internally in some species. The bladder

neg: Mollusca exuded mucus and microscopic, muscle-powered "hairs" called cilia play various important roles. The generalized mollusc has two paired nerve cords, or three in bivalves. The brain, in species that have one, encircles the esophagus. Most molluscs have eyes, and all have sensors to detect chemicals, vibrations, and touch. The simplest type of molluscan reproductive system relies on external fertilization, but more complex variations occur. All produce eggs, from which may emerge trochophore larvae, more complex veliger larvae, or miniature adults.The coelomic cavity is reduced.They have an open circulatory system and kidney-like organs for excretion. Good evidence exists for the appearance

neg: Marine invertebrates a complex digestive system using microscopic, muscle-powered hairs called cilia to exude mucus. The generalized mollusc has two paired nerve cords (three in bivalves). The brain, in species that have one, encircles the esophagus. Most molluscs have eyes and all have sensors detecting chemicals, vibrations, and touch. The simplest type of molluscan reproductive system relies on external fertilization, but more complex variations occur. All produce eggs, from which may emerge trochophore larvae, more complex veliger larvae, or miniature adults. The depiction is rather similar to modern monoplacophorans, and some suggest it may resemble very early molluscs. Good evidence exists for

neg: Reproductive medicine fertility. The field cooperates with and overlaps mainly with reproductive endocrinology and infertility, sexual medicine and andrology, but also to some degree with gynecology, obstetrics, urology, genitourinary medicine, medical endocrinology, pediatric endocrinology, genetics, and psychiatry. Assessment methods could include: imaging techniques, laboratory methods and reproductive surgery. Treatment methods include counseling, pharmacology (e.g. fertility medication), surgery, and other methods. In vitro fertilization has evolved as a major treatment modality that has enabled the study of the embryo prior to implantation. Specialists in reproductive medicine usually undergo training in obstetrics and gynecology followed by training in reproductive endocrinology and infertility, or in

neg: Sexual reproduction one sex and changing to the other. In at least one hermaphroditic species, self-fertilization occurs when the eggs and sperm are released together. Internal self-fertilization may occur in some other species. One fish species does not reproduce by sexual reproduction but uses sex to produce offspring; "Poecilia formosa" is a unisex species that uses a form of parthenogenesis called gynogenesis, where unfertilized eggs develop into embryos that produce female offspring. "Poecilia formosa" mate with males of other fish species that use internal fertilization, the sperm does not fertilize the eggs but stimulates the growth of the eggs which develops into