query: the release of an egg cell is called

pos: Ovarian follicle Ovarian follicle An ovarian follicle is a roughly spheroid cellular aggregation set found in the ovaries. It secretes hormones that influence stages of the menstrual cycle. Women begin puberty with about 400,000 follicles, each with the potential to release an egg cell (ovum) at ovulation for fertilization. These eggs are developed once every menstrual cycle. Ovarian follicles are the basic units of female reproductive biology. Each of them contains a single oocyte (immature ovum or egg cell). These structures are periodically initiated to grow and develop, culminating in ovulation of usually a single competent oocyte in humans. They also consist

pos: Female reproductive system it reaches the uterus, which signals the beginning of pregnancy. The ovaries are small, paired organs located near the lateral walls of the pelvic cavity. These organs are responsible for the production of the egg cells (ova) and the secretion of hormones. The process by which the egg cell (ovum) is released is called ovulation. The speed of ovulation is periodic and impacts directly to the length of a menstrual cycle. After ovulation, the egg cell is captured by the Fallopian tube, after traveling down the Fallopian tube to the uterus, occasionally being fertilized on its way by an incoming

neg: Double fertilization to release the two sperm in the megagametophyte. The ovules are 8 in number and arranged in the form of 3+2+3 (from top to bottom) i.e 3 antipodal cells, 2 polar central cells, 2 synergids & 1 egg cell. One sperm fertilizes the egg cell and the other sperm combines with the two polar nuclei of the large central cell of the megagametophyte. The haploid sperm and haploid egg combine to form a diploid zygote,the process being called syngamy , while the other sperm and the two haploid polar nuclei of the large central cell of the megagametophyte form a

neg: Gynoecium apical placentation, respectively). In flowering plants, the "ovule" (from Latin "ovulum" meaning small egg) is a complex structure born inside ovaries. The ovule initially consists of a stalked, integumented "megasporangium" (also called the "nucellus"). Typically, one cell in the megasporangium undergoes meiosis resulting in one to four megaspores. These develop into a megagametophyte (often called the embryo sac) within the ovule. The megagametophyte typically develops a small number of cells, including two special cells, an egg cell and a binucleate central cell, which are the gametes involved in double fertilization. The central cell, once fertilized by a sperm cell from

neg: Egg cell into an embryo inside the ovule. The ovule in turn develops into a seed and in many cases the plant ovary develops into a fruit to facilitate the dispersal of the seeds. Upon germination, the embryo grows into a seedling. In the moss "Physcomitrella patens", the Polycomb protein FIE is expressed in the unfertilised egg cell (Figure, right) as the blue colour after GUS staining reveals. Soon after fertilisation the FIE gene is inactivated (the blue colour is no longer visible, left) in the young embryo. In algae, the egg cell is often called oosphere. "Drosophila" oocytes develop in individual

neg: Egg cell which will grow into a new diploid individual (sporophyte). In seed plants, a structure called ovule, which contains the female gametophyte. The gametophyte produces an egg cell. After fertilization, the ovule develops into a seed containing the embryo. In flowering plants, the female gametophyte (sometimes referred to as the embryo sac) has been reduced to just eight cells inside the ovule. The gametophyte cell closest to the micropyle opening of the ovule develops into the egg cell. Upon pollination, a pollen tube delivers sperm into the gametophyte and one sperm nucleus fuses with the egg nucleus. The resulting zygote develops

neg: Egg cell birth, or just after the egg leaves the mother's body. Some fish, reptiles and many invertebrates use this technique. Nearly all land plants have alternating diploid and haploid generations. Gametes are produced by the gametophyte, which is the haploid generation. The female gametophyte produces structures called archegonia, and the egg cells form within them via mitosis. The typical bryophyte archegonium consists of a long neck with a wider base containing the egg cell. Upon maturation, the neck opens to allow sperm cells to swim into the archegonium and fertilize the egg. The resulting zygote then gives rise to an embryo,

neg: Somatic cell nuclear transfer nucleus of the donor egg cell is removed and discarded, leaving it 'deprogrammed.' What is left is a somatic cell and an denucleated egg cell. These are then fused by inserting the somatic cell into the 'empty' ovum. After being inserted into the egg, the somatic cell nucleus is reprogrammed by its host egg cell. The ovum, now containing the somatic cell's nucleus, is stimulated with a shock and will begin to divide. The egg is now viable and capable of producing an adult organism containing all the necessary genetic information from just one parent. Development will ensue normally and

neg: Egg as food shorten their length of freshness. The shape of an egg resembles a prolate spheroid with one end larger than the other and has cylindrical symmetry along the long axis. An egg is surrounded by a thin, hard shell. Thin membranes exist inside the shell. The egg yolk is suspended in the egg white by one or two spiral bands of tissue called the chalazae (from the Greek word χάλαζα, meaning 'hailstone' or 'hard lump'). The larger end of the egg contains an air cell that forms when the contents of the egg cool down and contract after it is laid.

neg: Human embryogenesis Human embryogenesis Human embryogenesis refers to the development and formation of the human embryo. It is characterised by the process of cell division and cellular differentiation of the embryo that occurs during the early stages of development. In biological terms, human development entails growth from a one-celled zygote to an adult human being. Fertilisation occurs when the sperm cell successfully enters and fuses with an egg cell (ovum). The genetic material of the sperm and egg then combine to form a single cell called a zygote and the germinal stage of prenatal development commences. Embryogenesis covers the first eight weeks

neg: Egg cell assumption that mammals also reproduced via eggs. Karl Ernst von Baer discovered the mammalian ovum in 1827, and Edgar Allen discovered the human ovum in 1928. The fusion of spermatozoa with ova (of a starfish) was observed by Oskar Hertwig in 1876. In animals, egg cells are also known as ova (singular ovum, from the Latin word "ovum" meaning egg or egg cell). The term ovule in animals is used for the young ovum of an animal. In vertebrates, ova are produced by female gonads (sexual glands) called ovaries. A number of ova are present at birth in mammals and

neg: Gamete Gamete A gamete (; from Ancient Greek γαμετή "gamete" from gamein "to marry") is a haploid cell that fuses with another haploid cell during fertilization (conception) in organisms that sexually reproduce. In species that produce two morphologically distinct types of gametes, and in which each individual produces only one type, a female is any individual that produces the larger type of gamete—called an ovum (or egg)—and a male produces the smaller tadpole-like type—called a sperm. In short a gamete is an egg (female gamete) or a sperm (male gamete). This is an example of anisogamy or heterogamy, the condition in

neg: Egg cell Egg cell The egg cell, or ovum (plural ova), is the female reproductive cell (gamete) in oogamous organisms. The egg cell is typically not capable of active movement, and it is much larger (visible to the naked eye) than the motile sperm cells. When egg and sperm fuse, a diploid cell (the zygote) is formed, which rapidly grows into a new organism. While the non-mammalian animal egg was obvious, the doctrine "ex ovo omne vivum" ("every living [animal comes from] an egg"), associated with William Harvey (1578–1657), was a rejection of spontaneous generation and preformationism as well as a bold

neg: Fish development Fish development The development of fishes is unique in some specific aspects compared to the development of other animals. Most bony fish eggs are referred to as telolecithal which means that most of the egg cell cytoplasm is yolk. The yolky end of the egg (the vegetal pole) remains homogenous while the other end (the animal pole) undergoes cell division. Cleavage, or initial cell division, can only occur in a region called the blastodisc, a yolk free region located at the animal pole of the egg. The fish zygote is meroblastic, meaning the early cell divisions are not complete. This

neg: Oocyte activation Oocyte activation Oocyte (or ovum/egg) activation is a series of processes that occur in the oocyte during fertilization. Sperm entry causes calcium release into the oocyte. In mammals, this has been proposed to be caused by the introduction of phospholipase C isoform zeta (PLCζ) from the sperm cytoplasm, although this remains to be established definitively. Activation of the ovum includes the following events: The sperm may trigger egg activation via the interaction between a sperm protein and an egg surface receptor. Izumo is the sperm cell signal, that will trigger the egg receptor Juno. This receptor is activated by the

neg: Fish development the fish belongs to the corresponding gender. Fish development The development of fishes is unique in some specific aspects compared to the development of other animals. Most bony fish eggs are referred to as telolecithal which means that most of the egg cell cytoplasm is yolk. The yolky end of the egg (the vegetal pole) remains homogenous while the other end (the animal pole) undergoes cell division. Cleavage, or initial cell division, can only occur in a region called the blastodisc, a yolk free region located at the animal pole of the egg. The fish zygote is meroblastic, meaning the

neg: Partial cloning a donor in so-called “nuclear transfer” experiments where an old nucleus is transferred into a recipient egg whose own nuclear material has been removed. The “reconstructed” egg is then prompted to engage development and develops through an embryonic stage that results, once the embryo is implanted into a surrogate mother, into a new born. Thus an old cell can give rise to a newborn, which has a typical lifespan: the age of the donor cell is “wiped clean” and returned to a youthful state. Notably, in classical animal cloning the rejuvenation process involves a return to an embryonic form. Thus

neg: Development of the human body of the embryo that occurs during the early stages of development. In biological terms, human development entails growth from a one-celled zygote to an adult human being. Fertilisation occurs when the sperm cell successfully enters and fuses with an egg cell (ovum). The genetic material of the sperm and egg then combine to form a single cell called a zygote and the germinal stage of prenatal development commences. Embryogenesis covers the first eight weeks of development; at the beginning of the ninth week the embryo is termed a fetus. The germinal stage refers to the time from fertilization through the

neg: Cellular differentiation a sperm fertilizes an egg and creates a single cell that has the potential to form an entire organism. In the first hours after fertilization, this cell divides into identical cells. In humans, approximately four days after fertilization and after several cycles of cell division, these cells begin to specialize, forming a hollow sphere of cells, called a blastocyst. The blastocyst has an outer layer of cells, and inside this hollow sphere, there is a cluster of cells called the inner cell mass. The cells of the inner cell mass go on to form virtually all of the tissues of

neg: Sex and female forms—spermatozoa and egg cells. These gametes combine to form embryos which develop into a new organism. The male gamete, a spermatozoon (produced in vertebrates within the testes), is a small cell containing a single long flagellum which propels it. Spermatozoa are extremely reduced cells, lacking many cellular components that would be necessary for embryonic development. They are specialized for motility, seeking out an egg cell and fusing with it in a process called fertilization. Female gametes are egg cells (produced in vertebrates within the ovaries), large immobile cells that contain the nutrients and cellular components necessary for a

neg: Egg is usually motile whereas the female gamete cell, the ovum, is generally larger and sessile. The male and female gametes combine to produce the zygote cell. In multicellular organisms the zygote subsequently divides in an organised manner into smaller more specialised cells, so that this new individual develops into an embryo. In most animals the embryo is the sessile initial stage of the individual life cycle, and is followed by the emergence (that is, the hatching) of a motile stage. The zygote or the ovum itself or the sessile organic vessel containing the developing embryo may be called the egg.

neg: Egg as food Chicken eggs are graded according to the size of this air cell, measured during candling. A very fresh egg has a small air cell and receives a grade of AA. As the size of the air cell increases and the quality of the egg decreases, the grade moves from AA to A to B. This provides a way of testing the age of an egg: as the air cell increases in size due to air being drawn through pores in the shell as water is lost, the egg becomes less dense and the larger end of the egg will rise

neg: Oscar Hertwig leader in the field of comparative and causal animal-developmental history. He also wrote a leading textbook. By studying sea urchins he proved that fertilization occurs due to the fusion of a sperm and egg cell. He recognized the role of the cell nucleus during inheritance and chromosome reduction during meiosis: in 1876, he published his findings that fertilization includes the penetration of a spermatozoon into an egg cell. Hertwig's experiments with frog eggs revealed the 'long axis rule', or Hertwig rule. According to this rule, cell divides along its long axis. In 1885 Hertwig wrote that "nuclein" (later called nucleic

neg: Sex other aspects (anisogamy). By convention, the larger gamete (called an ovum, or egg cell) is considered female, while the smaller gamete (called a spermatozoon, or sperm cell) is considered male. An individual that produces exclusively large gametes is female, and one that produces exclusively small gametes is male. An individual that produces both types of gametes is a hermaphrodite; in some cases hermaphrodites are able to self-fertilize and produce offspring on their own, without a second organism. Most sexually reproducing animals spend their lives as diploid, with the haploid stage reduced to single-cell gametes. The gametes of animals have male

neg: Hornet tree bark. The cells are arranged in horizontal layers named combs, each cell being vertical and closed at the top. An egg is then laid in each cell. After 5–8 days, the egg hatches, and in the next two weeks, the larva undergoes its five stages. During this time, the queen feeds it a protein-rich diet of insects. Then, the larva spins a silk cap over the cell's opening and, during the next two weeks, transforms into an adult, a process called metamorphosis. The adult then eats its way through the silk cap. This first generation of workers, invariably females,

neg: Beekeeping to fertilize an egg as she lays it; if she does so, it develops into a female worker bee; if she lays an unfertilized egg it becomes a male drone. She decides which type of egg to lay depending on the size of the open brood cell she encounters on the comb. In a small worker cell, she lays a fertilized egg; if she finds a larger drone cell, she lays an unfertilized drone egg. All the time that the queen is fertile and laying eggs she produces a variety of pheromones, which control the behavior of the bees in

neg: Developmental biology general rules would be expected. The sperm and egg fuse in the process of fertilization to form a fertilized egg, or zygote. This undergoes a period of divisions to form a ball or sheet of similar cells called a blastula or blastoderm. These cell divisions are usually rapid with no growth so the daughter cells are half the size of the mother cell and the whole embryo stays about the same size. They are called cleavage divisions. Morphogenetic movements convert the cell mass into a three layered structure consisting of multicellular sheets called ectoderm, mesoderm and endoderm, which are known

neg: Yolk different from a cell membrane. The yolk is mostly extracellular to the oolemma, being not accumulated inside the cytoplasm of the egg cell (as occurs in frogs), contrary to the claim that the avian egg cell (in strict sense) and its yolk are a single giant cell. After the fertilization, the cleavage of the embryo leads to the formation of the germinal disc. As food, the chicken egg yolk is a major source of vitamins and minerals. It contains all of the egg's fat and cholesterol, and nearly half of the protein. If left intact when an egg is fried,

neg: Western honey bee deposits a single egg into each cell of a honeycomb prepared by worker bees. The egg hatches into a legless, eyeless larva fed by "nurse" bees (worker bees who maintain the interior of the colony). After about a week, the larva is sealed in its cell by the nurse bees and begins its pupal stage. After another week, it emerges as an adult bee. It is common for defined regions of the comb to be filled with young bees (also called "brood"), while others are filled with pollen and honey stores. Worker bees secrete the wax used to build the

neg: Gynoecium the pollen becomes the first cell of the endosperm, and the egg cell once fertilized become the zygote that develops into the embryo. The gap in the integuments through which the pollen tube enters to deliver sperm to the egg is called the micropyle. The stalk attaching the ovule to the placenta is called the funiculus. Stigmas can vary from long and slender to globe-shaped to feathery. The stigma is the receptive tip of the carpel(s), which receives pollen at pollination and on which the pollen grain germinates. The stigma is adapted to catch and trap pollen, either by combining

neg: Egg medium-sized eggs with some yolk are called "mesolecithal", and large eggs with a large concentrated yolk are called "macrolecithal". This classification of eggs is based on the eggs of chordates, though the basic principle extends to the whole animal kingdom. Small eggs with little yolk are called microlecithal. The yolk is evenly distributed, so the cleavage of the egg cell cuts through and divides the egg into cells of fairly similar sizes. In sponges and cnidarians the dividing eggs develop directly into a simple larva, rather like a morula with cilia. In cnidarians, this stage is called the planula, and

neg: DNA profiling low cost and ease of set-up and operation, AmpFLP remains popular in lower income countries. Using PCR technology, DNA analysis is widely applied to determine genetic family relationships such as paternity, maternity, siblingship and other kinships. During conception, the father's sperm cell and the mother's egg cell, each containing half the amount of DNA found in other body cells, meet and fuse to form a fertilized egg, called a zygote. The zygote contains a complete set of DNA molecules, a unique combination of DNA from both parents. This zygote divides and multiplies into an embryo and later, a full human

neg: Egg cell egg chambers that are supported by nurse cells and surrounded by somatic follicle cells. The nurse cells are large polyploid cells that synthesize and transfer RNA, proteins and organelles to the oocytes. This transfer is followed by the programmed cell death (apoptosis) of the nurse cells. During the course of oogenesis, 15 nurse cells die for every oocyte that is produced. In addition to this developmentally regulated cell death, egg cells may also undergo apoptosis in response to starvation and other insults. Egg cell The egg cell, or ovum (plural ova), is the female reproductive cell (gamete) in oogamous organisms.

neg: Dolly (sheep) and had three mothers: one provided the egg, another the DNA, and a third carried the cloned embryo to term. She was created using the technique of somatic cell nuclear transfer, where the cell nucleus from an adult cell is transferred into an unfertilized oocyte (developing egg cell) that has had its cell nucleus removed. The hybrid cell is then stimulated to divide by an electric shock, and when it develops into a blastocyst it is implanted in a surrogate mother. Dolly was the first clone produced from a cell taken from an adult mammal. The production of Dolly showed

neg: Prenatal development body of the uterus and into the Fallopian tubes. Fertilization of the egg cell (ovum), usually takes place in one of the Fallopian tubes. Many sperm are released with the possibility of just one sperm cell managing to adhere to and enter the thick protective shell-like layer surrounding the ovum. The first sperm that penetrates fully into the egg donates its genetic material (DNA). The egg then polarizes, repelling any additional sperm. The resulting combination is called a zygote, a new and genetically unique organism. The term "conception" refers variably to either fertilization or to formation of the conceptus after

neg: Granulosa cell Granulosa cell A granulosa cell or follicular cell is a somatic cell of the sex cord that is closely associated with the developing female gamete (called an oocyte or egg) in the ovary of mammals. In the primary ovarian follicle, and later in follicle development (folliculogenesis), granulosa cells advance to form a multilayered cumulus oophorus surrounding the oocyte in the preovulatory or antral (or Graafian) follicle. The major functions of granulosa cells include the production of sex steroids, as well as myriad growth factors thought to interact with the oocyte during its development. The sex steroid production begins with follicle-stimulating

neg: Granulosa cell can be performed "in vitro". Plating density (number of cells per volume of culture medium) plays a critical role for the differentiation. A lower plating density makes granulosa cells exhibit estrogen production, while a higher plating density makes them appear as progesterone producing theca lutein cells. Granulosa cell A granulosa cell or follicular cell is a somatic cell of the sex cord that is closely associated with the developing female gamete (called an oocyte or egg) in the ovary of mammals. In the primary ovarian follicle, and later in follicle development (folliculogenesis), granulosa cells advance to form a multilayered cumulus

neg: Root-knot nematode studied, free-living nematode "Caenorhabditis elegans". Embryogenesis has also been studied, and the stages of development are easily identifiable with a phase contrast microscope following preparation of an egg mass squash. The egg is formed as one cell, with two-cell, four-cell and eight-cell stages recognisable. Further cell division leads to the tadpole stage, with further elongation resulting in the first stage juvenile, which is roughly four times as long as the egg. The J1 stage of "C. elegans" has 558 cells, and the J1 of "M. javanica" likely has a similar number, since all nematodes are morphologically and anatomically similar. The

neg: Parthenogenesis and therefore susceptibility to adverse mutations that might occur) and benefits (reproduction without the need for a male) associated with parthenogenesis. Parthenogenesis is distinct from artificial animal cloning, a process where the new organism is necessarily genetically identical to the cell donor. In cloning, the nucleus of a diploid cell from a donor organism is inserted into an enucleated egg cell and the cell is then stimulated to undergo continued mitosis, resulting in an organism that is genetically identical to the donor. Parthenogenesis is different, in that it originates from the genetic material contained within an egg cell and the

neg: XXYY syndrome occurs as a random event during the formation of reproductive cells (eggs and sperm). An error in cell division called nondisjunction results in a reproductive cell with an abnormal number of chromosomes. In 48,XXYY syndrome, the extra sex chromosomes almost always come from a sperm cell. Nondisjunction may cause a sperm cell to gain two extra sex chromosomes, resulting in a sperm cell with three sex chromosomes (one X and two Y chromosomes). If that sperm cell fertilizes a normal egg cell with one X chromosome, the resulting child will have two X chromosomes and two Y chromosomes in each

neg: Haplogroup to provide energy to the cell. Mitochondria are thought to be reduced descendants of symbiotic bacteria that were once free living. One indication that mitochondria were once free living is that each contains a circular DNA, called mitochondrial DNA (mtDNA), whose structure is more similar to bacteria than eukaryotic organisms (see endosymbiotic theory). The overwhelming majority of a human's DNA is contained in the chromosomes in the nucleus of the cell, but mtDNA is an exception. An individual inherits his or her cytoplasm and the organelles contained by that cytoplasm exclusively from the maternal ovum (egg cell); sperm only pass

neg: Patau syndrome formation of reproductive cells (eggs and sperm). An error in cell division called non-disjunction can result in reproductive cells with an abnormal number of chromosomes. For example, an egg or sperm cell may gain an extra copy of the chromosome. If one of these atypical reproductive cells contributes to the genetic makeup of a child, the child will have an extra chromosome 13 in each of the body's cells. Mosaic Patau syndrome is also not inherited. It occurs as a random error during cell division early in fetal development. Patau syndrome due to a translocation can be inherited. An unaffected

neg: Somatic cell nuclear transfer Somatic cell nuclear transfer In genetics and developmental biology, somatic cell nuclear transfer (SCNT) is a laboratory strategy for creating a viable embryo from a body cell and an egg cell. The technique consists of taking an enucleated oocyte (egg cell) and implanting a donor nucleus from a somatic (body) cell. It is used in both therapeutic and reproductive cloning. Dolly the Sheep became famous for being the first successful case of the reproductive cloning of a mammal. In January 2018, a team of scientists in Shanghai announced the successful cloning of two female crab-eating macaques (named Zhong Zhong and

neg: Endosperm egg cell, forming a zygote, while the other sperm nucleus usually fuses with the binucleate central cell, forming a primary endosperm cell (its nucleus is often called the "triple fusion nucleus"). That cell created in the process of double fertilization develops into the endosperm. Because it is formed by a separate fertilization, the endosperm constitutes an organism separate from the growing embryo. About 70% of angiosperm species have endosperm cells that are polyploid. These are typically triploid (containing three sets of chromosomes), but can vary widely from diploid (2n) to 15n. One species of flowering plant, "Nuphar polysepala", has been

neg: Somatic cell nuclear transfer states, the "Convention" has been signed by 31 and ratified by 18. The "Additional Protocol" has been signed by 29 member nations and ratified by 14. Somatic cell nuclear transfer In genetics and developmental biology, somatic cell nuclear transfer (SCNT) is a laboratory strategy for creating a viable embryo from a body cell and an egg cell. The technique consists of taking an enucleated oocyte (egg cell) and implanting a donor nucleus from a somatic (body) cell. It is used in both therapeutic and reproductive cloning. Dolly the Sheep became famous for being the first successful case of the reproductive

neg: Karyogamy and egg (oocyte) DNA. Drugs such as griseofulvin that interfere with microtubules prevent the fusion of the sperm and egg pronuclei. The gene KAR2 which plays a large role in karyogamy has a mammalian analog called Bib/GRP78. In both cases, genetic material is combined to create a diploid cell that has greater genetic diversity than either original source. Instead of fusing in the same way as lower eukaryotes do in karyogamy, the sperm nucleus vesiculates and its DNA decondenses. The sperm centriole acts as a microtubule organizing center and forms an aster which extends throughout the egg until contacting the

neg: Mitochondrial replacement therapy egg from the donor. As with MST, a small amount of cytoplasm from the donor egg may be transferred, and as with MST, the fertilized egg is allowed to form a blastocyst, which can then be investigated with preimplantation genetic diagnosis to check for mitochondrial mutations, prior to being implanted in the recipient's uterus. In polar body transfer, a polar body (a small cell with very little cytoplasm that is created when an egg cell divides) from the recipient is used in its entirety, instead of using nuclear material extracted from the recipient's normal egg; this can be used in

neg: Double fertilization double fertilization occurs in the sexual reproduction of an order of gymnosperms commonly known as Gnetales. Specifically, this event has been documented in both "Ephedra" and "Gnetum", a subset of Gnetophytes. In "Ephedra nevadensis", a single binucleate sperm cell is deposited into the egg cell. Following the initial fertilization event, the second sperm nucleus is diverted to fertilize an additional egg nucleus found in the egg cytoplasm. In most other seed plants, this second 'ventral canal nucleus' is normally found to be functionally useless. In "Gnetum gnemon", numerous free egg nuclei exist in female cytoplasm inside the female gametophyte. Succeeding

neg: Gametophyte sperm by mitosis. In gymnosperms the megagametophyte consists of several thousand cells and produces one to several archegonia, each with a single egg cell. The gametophyte becomes a food storage tissue in the seed. In angiosperms, the megagametophyte is reduced to only a few nuclei and cells, and is sometimes called the embryo sac. A typical embryo sac contains seven cells and eight nuclei, one of which is the egg cell. Two nuclei fuse with a sperm nucleus to form endosperm, which becomes the food storage tissue in the seed. Gametophyte A gametophyte () is one of the two alternating

neg: Germ cell The first way is called preformistic and involves that the cells destined to become germ cells inherit the specific germ cell determinants present in the germ plasm (specific area of the cytoplasm) of the egg (ovum). The unfertilized egg of most animals is asymmetrical: different regions of the cytoplasm contain different amounts of mRNA and proteins. The second way is found in birds and mammals, where germ cells are not specified by such determinants but by signals controlled by zygotic genes. In mammals, a few cells of the early embryo are induced by signals of neighboring cells to become primordial

neg: Mitochondrion mitochondria are inherited from one parent only. In humans, when an egg cell is fertilized by a sperm, the egg nucleus and sperm nucleus each contribute equally to the genetic makeup of the zygote nucleus. In contrast, the mitochondria, and therefore the mitochondrial DNA, usually come from the egg only. The sperm's mitochondria enter the egg, but do not contribute genetic information to the embryo. Instead, paternal mitochondria are marked with ubiquitin to select them for later destruction inside the embryo. The egg cell contains relatively few mitochondria, but it is these mitochondria that survive and divide to populate the

neg: Immature teratoma Immature teratoma A teratoma is a tumor of germ cell origin, containing tissues from more than one germ cell line. It can be ovarian or testicular in its origin. An ovarian teratoma is a tumor that arises from egg cells in the ovary. Histologically, it is of two types: mature cystic teratoma and immature teratoma. A mature cystic teratoma, often called a dermoid cyst, is a benign non-cancerous tumor. Malignant transformation (most often to squamous cell carcinoma) is observed only in rare cases. A mature cycstic teratoma is most frequently diagnosed in women during their reproductive ages, but can occur

neg: Polar body risk of diagnostic error, for instance due to the degradation of the genetic material or events of recombination that lead to heterozygous first polar bodies. Polar body A polar body is a small haploid cell that is formed concomitantly as an egg cell during oogenesis, but which generally does not have the ability to be fertilized. When certain diploid cells in animals undergo cytokinesis after meiosis to produce egg cells, they sometimes divide unevenly. Most of the cytoplasm is segregated into one daughter cell, which becomes the egg or ovum, while the smaller "polar bodies" only get a small amount

neg: Polar body Polar body A polar body is a small haploid cell that is formed concomitantly as an egg cell during oogenesis, but which generally does not have the ability to be fertilized. When certain diploid cells in animals undergo cytokinesis after meiosis to produce egg cells, they sometimes divide unevenly. Most of the cytoplasm is segregated into one daughter cell, which becomes the egg or ovum, while the smaller "polar bodies" only get a small amount of cytoplasm. They frequently die (apoptosis) and disappear, but in some cases they remain and can be important in the life cycle of the organism.

neg: Sperm Non-motile sperm cells called spermatia lack flagella and therefore cannot swim. Spermatia are produced in a spermatangium. Because spermatia cannot swim, they depend on their environment to carry them to the egg cell. Some red algae, such as "Polysiphonia", produce non-motile spermatia that are spread by water currents after their release. The spermatia of rust fungi are covered with a sticky substance. They are produced in flask-shaped structures containing nectar, which attract flies that transfer the spermatia to nearby hyphae for fertilization in a mechanism similar to insect pollination in flowering plants. Fungal spermatia (also called pycniospores, especially in the

neg: Cell potency cell lineages if injected into another blastocyst. On the other hand, several marked differences can be observed between the pre- and post-implantation epiblasts, such as their difference in morphology, in which the epiblast after implantation changes its morphology into a cup-like shape called the "egg cylinder" as well as chromosomal alteration in which one of the X-chromosomes under random inactivation in the early stage of the egg cylinder, known as X-inactivation. During this development, the egg cylinder epiblast cells are systematically targeted by Fibroblast growth factors, Wnt signaling, and other inductive factors via the surrounding yolk sac and the trophoblast

neg: Melipona quadrifasciata in each growing stage. When a cell has been completed, the queen will fixate on the cell for inspection and push away workers from the cell. A worker will provision food into the cell and quickly retreat. Sometimes, when the queen is not around, a worker will lay an egg in the cell and quickly retreat from the area similar to when provisioning cells. During worker oviposition, or egg laying, the worker will be quiet with her wings closed and keep her body completely still as not to attract the queen. Worker oviposition will last an average of 7 seconds.

neg: Ehud Shapiro a mathematical entity called a cell lineage tree. The root of the tree represents the fertilized egg, the leaves of the tree represent the person's extant cells, and branches in the tree capture every single cell division in the person's history. Science knows precisely the cell lineage tree of only one organism a worm called Caenorhabditis elegans that reaches its full size of 1 millimeter and 1,000 cells in 36 hours. By comparison, a newborn mouse, weighing only a few grams, has about 1 billion cells. An average person has about 100 trillion cells. Understanding the structure and dynamics of

neg: Karyogamy cell, called a zygote or zygospore can then enter meiosis (a process of chromosome duplication, recombination, and division, to produce four new haploid cells), or continue to divide by mitosis. Mammalian fertilization uses a comparable process to combine haploid sperm and egg cells (gametes) to create a diploid fertilized egg. The term karyogamy comes from the Greek "karyo-" (from κάρυον "karyon") meaning "nut" and γάμος "gamos", meaning "marriage". Haploid organisms such as fungi, yeast, and algae can have complex cell cycles, in which the choice between sexual or asexual reproduction is fluid, and often influenced by the environment. Some organisms,

neg: Ibaliidae and pronounced. The female antenna consists of 11 segments, while the male antenna consists of 13 segments. A large portion of the pronotum is well developed, called the dorsal pronotal area, with scutellar processes. The marginal cell of the forewing is elongated and thin. The gaster is long and pronouncedly compressed laterally. The seventh tergum is large in females. An apical tubular process is present on the second tarsomere of the hind leg. The metafemur is short, no longer than the metacoxa. The female lays the egg by oviposition through the oviposition shafts created by Siricidae, and the egg is

neg: Ovarian pregnancy a link to the intrauterine device (IUD), however, it cannot be concluded that this is causative as it could be that IUDs prevent other but not ovarian pregnancies. Some have suggested that patients who undergo IVF therapy are at higher risk for ovarian pregnancy. An ovarian pregnancy is usually understood to begin when a mature egg cell is not expelled or picked up from its follicle and a sperm enters the follicle and fertilizes the egg, giving rise to an intrafollicular pregnancy. It has also been debated that an egg cell fertilized outside of the ovary could implant on the

neg: Melipona quadrifasciata A worker's egg is about the size of eggs laid by the queen. The queen briefly inspects the cell before inserting her metasoma. Usually, if a worker egg is found, it is eaten by the queen. The duration of queen oviposition is notably longer than worker oviposition, lasting an average of 24.5 seconds. After the queen has deposited an egg, there is usually a slight delay in "M. quadrifasciata" workers before operculation, or closing of the cell, occurs. It has been found in "Melipona quadrifasciata" that caste determination is both genetic and environmental. "Melipona" cells which produce workers (and males)

neg: Embryomics present inside, and surface antigens present on the surface of, the cells making up the embryo. For any given cell type, these RNA and protein markers reflect the genes characteristically active in that cell type. The catalog of all these cell types and their characteristic markers is known as the organism's embryome. The word is a portmanteau of embryo and genome. “Embryome” may also refer to the totality of the physical cell markers themselves. As an embryo develops from a fertilized egg, the single egg cell splits into many cells, which grow in number and migrate to the appropriate locations

neg: Sex selection the father's sperm in a technique called in vitro fertilization (IVF). "In vitro" is Latin for "within glass". Fertilized eggs are called embryos. As the embryos develop through mitosis, they are separated by sex. Embryos of the desired gender are implanted back in the mother's uterus. Prior to fertilization with IVF, the fertilized eggs can be genetically biopsied with preimplantation genetic diagnosis (PGD) to increase fertilization success. Once an embryo grows to a 6-8 cell size, a small laser incision in the egg membrane (zona pellucida) allows safe removal of one of the cells. Every cell in the embryo contains

neg: Somatic cell nuclear transfer treatment. For example, to treat a man with Parkinson's disease, a cell nucleus from one of his cells would be transplanted by SCNT into an egg cell from an egg donor, creating a unique lineage of stem cells almost identical to the patient's own cells. (There would be differences. For example, the mitochondrial DNA would be the same as that of the egg donor. In comparison, his own cells would carry the mitochondrial DNA of his mother.) Potentially millions of patients could benefit from stem cell therapy, and each patient would require a large number of donated eggs in order

neg: Dominant white are unaffected. A mosaic mutation may or may not be inheritable, depending on the cell populations affected. Though this is not always the case, genetic mutations can occur spontaneously in one sex cell of a parent during gametogenesis. In these cases, called germline mutations, the mutation will be present in the single-celled zygote conceived from the affected sperm or egg cell, and the condition can be inherited by the next generation. In humans, a skin condition called piebaldism is caused by more than a dozen distinct mutations in the "KIT" gene. Piebaldism in humans is characterized by a white forelock,

neg: Hertwig rule Hertwig rule Hertwig's rule or 'long axis rule' states that a cell divides along its long axis. It was introduced by german zoologist Oscar Hertwig in 1884. The rule emphasizes the cell shape to be a default mechanism of spindle apparatus orientation. Hertwig's rule predicts cell division orientation, that is important for tissue architecture, cell fate and morphogenesis. In Hertwig's experiments the orientation of divisions of the frog egg was studied. Frog egg has a round shape and the first division occur in the random orientation. Hertwig compressed the egg between two parallel plates. The compression forced egg to change

neg: Egg cell of them divides repeatedly to give secretions of the uterine glands, ultimately forming a blastocyst. The ovum is one of the largest cells in the human body, typically visible to the naked eye without the aid of a microscope or other magnification device. The human ovum measures approximately 0.1 mm in diameter. Ooplasm (also: oöplasm) is the yolk of the ovum, a cell substance at its center, which contains its nucleus, named the germinal vesicle, and the nucleolus, called the germinal spot. The ooplasm consists of the cytoplasm of the ordinary animal cell with its spongioplasm and hyaloplasm, often called

neg: Cloning to create cloned human beings (called "reproductive cloning"), but rather to harvest stem cells that can be used to study human development and to potentially treat disease. While a clonal human blastocyst has been created, stem cell lines are yet to be isolated from a clonal source. Therapeutic cloning is achieved by creating embryonic stem cells in the hopes of treating diseases such as diabetes and Alzheimer's. The process begins by removing the nucleus (containing the DNA) from an egg cell and inserting a nucleus from the adult cell to be cloned. In the case of someone with Alzheimer's disease,

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: Cell cycle the need for cellular checkpoints. An alternative model of the cell cycle response to DNA damage has also been proposed, known as the postreplication checkpoint. Checkpoint regulation plays an important role in an organism's development. In sexual reproduction, when egg fertilization occurs, when the sperm binds to the egg, it releases signalling factors that notify the egg that it has been fertilized. Among other things, this induces the now fertilized oocyte to return from its previously dormant, G, state back into the cell cycle and on to mitotic replication and division. p53 plays an important role in triggering the control

neg: Egg and the small microlecithal eggs do not allow full development. Instead, the eggs hatch into larvae, which may be markedly different from the adult animal. In placental mammals, where the embryo is nourished by the mother throughout the whole fetal period, the egg is reduced in size to essentially a naked egg cell. Mesolecithal eggs have comparatively more yolk than the microlecithal eggs. The yolk is concentrated in one part of the egg (the "vegetal pole"), with the cell nucleus and most of the cytoplasm in the other (the "animal pole"). The cell cleavage is uneven, and mainly concentrated in

neg: Egg cell body (as in birds), or outside (as in many fish). After fertilization, an embryo develops, nourished by nutrients contained in the egg. It then hatches from the egg, outside the mother's body. See egg for a discussion of eggs of oviparous animals. The egg cell's cytoplasm and mitochondria are the sole means the egg is able to reproduce by mitosis and eventually form a blastocyst after fertilization. There is an intermediate form, the ovoviviparous animals: the embryo develops within and is nourished by an egg as in the oviparous case, but then it hatches inside the mother's body shortly before

neg: Egg A recent proposal suggests that the phylotypic animal body plans originated in cell aggregates before the existence of an egg stage of development. Eggs, in this view, were later evolutionary innovations, selected for their role in ensuring genetic uniformity among the cells of incipient multicellular organisms. Scientists often classify animal reproduction according to the degree of development that occurs before the new individuals are expelled from the adult body, and by the yolk which the egg provides to nourish the embryo. Vertebrate eggs can be classified by the relative amount of yolk. Simple eggs with little yolk are called "microlecithal",

neg: Eulaema meriana from the same generation and may even be sisters. Females work inside the nest at night, constructing cells and ovipositing. One egg is laid in each provisioned cell, and oviposition occurs after the provisions are tamped into the cell. Egg laying happens quickly as the female backs into the cell, holding the collar with her forelegs and inserting her posterior end into the cell. After laying the egg, the female pushes the resin collar in and spends a few hours covering the cell with mud. After this, the female begins to work on building a new brood cell. Larger nests

neg: Yolk other organisms, like algae, specially in the oogamous, can also accumulate resources in their female gametes. In gymnosperms, the remains of the female gametophyte serve also as food supply, and in flowering plants, the endosperm. In the avian egg, the yolk usually is some shade of yellow in color. It is spherical and is suspended in the egg white (known alternatively as albumen or glair/glaire) by one or two spiral bands of tissue called the chalazae. The yolk mass, together with the egg cell or ovum properly (after fertilization, the embryo) are enclosed by the vitelline membrane, whose structure is

neg: Cloning first to perform somatic-cell nuclear transfer using amphibian embryos – one of the first steps towards cloning. Reproductive cloning generally uses "somatic cell nuclear transfer" (SCNT) to create animals that are genetically identical. This process entails the transfer of a nucleus from a donor adult cell (somatic cell) to an egg from which the nucleus has been removed, or to a cell from a blastocyst from which the nucleus has been removed. If the egg begins to divide normally it is transferred into the uterus of the surrogate mother. Such clones are not strictly identical since the somatic cells may

neg: Human cloning Lanza at Advanced Cell Technology reported that they had replicated Mitalipov's results and further demonstrated the effectiveness by cloning adult cells using SCNT. In 2018, the first successful cloning of primates using somatic cell nuclear transfer, the same method as "Dolly" the sheep, with the birth of two live female clones (crab-eating macaques named "Zhong Zhong" and "Hua Hua") was reported. In somatic cell nuclear transfer ("SCNT"), the nucleus of a somatic cell is taken from a donor and transplanted into a host egg cell, which had its own genetic material removed previously, making it an enucleated egg. After the

neg: Megaspore center and two synergids. At the other end of the cell, a cell wall forms around the nuclei and forms the antipodals. Therefore, the resulting embryo sac is a seven-celled structure consisting of one central cell, one egg cell, two synergid cells, and three antipodal cells. The bisporic and tetrasporic patterns undergo varying processes and result in varying embryo sacs as well. In "Lilium" which has a tetrasporic pattern, the central cell of the embryo sac is 4N. Therefore, upon fertilization the endosperm will be 5N rather than the typical 3N. Megaspore Megaspores, also called macrospores, are a type of

neg: Melipona beecheii workers. The workers arrange the cells prior to the queen's arrival. When the queen arrives at a cell, the pre-discharge phase begins with a worker inserting themselves into a cell. The queen then performs oviposition, the process of depositing eggs into a cell. The queen taps the worker with her antennae and forelegs. This contact serves to signal the worker to insert larval food into the cell. Afterwards, the queen checks the cell and eats the trophic egg, an unfertilized egg that is made specifically for the queen’s nutrition. "Melipona beecheii" reproduction depends on many abiotic factors, including the time

neg: New York Stem Cell Foundation of passing on these diseases. Specifically, the team removed the nucleus of an unfertilized egg cell and replaced it with the nucleus of another donor’s egg cell, but, unlike the work of previous groups, the researchers lowered the temperature of the egg, increasing transfer success rate. NYSCF Researchers Derive Pluripotent Stem Cells from Human Egg Cells, Reported in "Nature" "Time" magazine-cited research led by NYSCF scientists Dieter Egli and Scott Noggle reprogrammed the adult skin cells from Type 1 diabetes patients to the pluripotent state by combining these cells with unfertilized donor eggs, as reported in "Nature". The scientists then

neg: Gametophyte distinct egg-producing and sperm-producing gametophytes, but these gametophytes develop from the same kind of spore inside the same sporangium; "Sphaerocarpos" is an example of such a plant. In the seed plants, the microgametophyte is called pollen. Seed plant microgametophytes consists of two or three cells when the pollen grains exit the sporangium. The megagametophyte develops within the megaspore of extant seedless vascular plants and within the megasporangium in a cone or flower in seed plants. In seed plants, the microgametophyte (pollen grain) travels to the vicinity of the egg cell (carried by a physical or animal vector), and produces two

neg: Hwang Woo-suk not cloned, embryos. The allegation involves the lines Hwang claims to have created at Seoul-based MizMedi Hospital. In November 22, 2016 Hwang received a certificate of patent on NT-1 technology by the Korean Intellectual Property Office. In the late 1990s, the method that scientists used in cloning was somatic cell nuclear transfer, which is the same procedure that was used to create Dolly the sheep. This laboratory technique begins when an egg is taken from a donor and the nucleus is removed from the egg, creating an enucleated egg. A cell, which contains DNA, is then taken from the animal

neg: Inositol trisphosphate important role in the induction of plasticity in cerebellar Purkinje cells. The slow block to polyspermy in the sea urchin is mediated by the PIP secondary messenger system. Activation of the binding receptors activates PLC, which cleaves PIP in the egg plasma membrane, releasing IP into the egg cell cytoplasm. IP diffuses to the ER, where it opens Ca channels. Huntington's disease occurs when the cytosolic protein Huntingtin (Htt) has an additional 35 glutamine residues added to its amino terminal region. This modified form of Htt is called Htt. Htt makes Type 1 IP receptors more sensitive to IP, which

neg: Cloning the nucleus from a skin cell of that patient is placed into an empty egg. The reprogrammed cell begins to develop into an embryo because the egg reacts with the transferred nucleus. The embryo will become genetically identical to the patient. The embryo will then form a blastocyst which has the potential to form/become any cell in the body. The reason why SCNT is used for cloning is because somatic cells can be easily acquired and cultured in the lab. This process can either add or delete specific genomes of farm animals. A key point to remember is that cloning

neg: Plant reproduction function of meiosis.” The gametophyte is the multicellular structure (plant) that is haploid, containing a single set of chromosomes in each cell. The gametophyte produces male or female gametes (or both), by a process of cell division called mitosis. In vascular plants with separate gametophytes, female gametophytes are known as mega gametophytes (mega=large, they produce the large egg cells) and the male gametophytes are called micro gametophytes (micro=small, they produce the small sperm cells). The fusion of male and female gametes (fertilization) produces a diploid zygote, which develops by mitotic cell divisions into a multicellular sporophyte. The mature sporophyte produces

neg: Jean-Paul Vincent Jean-Paul Vincent Jean-Paul Vincent is a developmental biologist working at the Francis Crick Institute. Vincent has conducted work on the Wnt signalling pathways that help to regulate cell-to-cell interactions. His work on cell signalling and behaviour has led to an improved understanding of diseases such as cancer in which fundamental biological processes are altered. Earlier in his career, he pioneered the use of caged dye technology to trace the cellular development of fruit fly embryos, and established a relationship between the alignment of frog embryos and their so-called subcortical rotation in the egg. Vincent was elected a Fellow of the

neg: Polystichum vestitum archegonia. When the sperm and the egg has matured and there is enough moisture on the prothallus, the antheridia release the spermatozoa which is attracted by the scent coming from the ripened egg and swims towards it to fertilize it. Once fertilized, the cell can divide and the new baby fern starts to grow with help from the prothallus, which supports it with nutrients. After a while when the fern has established its own root system and can continue growing on its own, the prothallus dies. A new life cycle can now begin when the fern grows towards maturity. The

neg: Down syndrome or ring chromosome. These contain additional material from chromosome 21 and occur in about 2.5% of cases. An isochromosome results when the two long arms of a chromosome separate together rather than the long and short arm separating together during egg or sperm development. Trisomy 21 (also known by the karyotype 47,XX,+21 for females and 47,XY,+21 for males) is caused by a failure of the 21st chromosome to separate during egg or sperm development (nondisjunction). As a result, a sperm or egg cell is produced with an extra copy of chromosome 21; this cell thus has 24 chromosomes. When combined

neg: Parthenogenesis in amphibians parthenogenesis where an egg begins to divide only after being pricked by a sperm cell, but without the genetic material of the sperm being used. There are two known mechanisms of gynogenesis. The first is an endomitotic event prior to meiosis, where the number of chromosomes in a cell doubles without cell division taking place. After meiosis each egg has the same ploidy (number of chromosomes) as the mother. This particular parthenogentic mechanism has been observed in unisexual "Ambystoma" species as well as "Glandirana rugosa". The second potential mechanism is apomixis, which produces a complete set of chromosomes through mitotic

neg: Cardiac excitation-contraction coupling is a Ca store within the cell and is located very close to the T-tubule. Activation of RyR2 causes it to open, releasing even more Ca into the cell, this release of calcium is called a calcium spark. This means that the initial flow of Ca into the cell, caused a larger release of Ca within the cell, therefore the process is called calcium induced calcium release (CICR). The increase in Ca, produced by CICR, now does two things. Firstly, it binds to the intracellular side of the DHPR, signalling the channels to close and preventing further influx of Ca

neg: Pregnancy standard deviation of 14 days when gestational age is estimated by first trimester ultrasound, and 16 days when estimated directly by last menstrual period. Through an interplay of hormones that includes follicle stimulating hormone that stimulates folliculogenesis and oogenesis creates a mature egg cell, the female gamete. Fertilization is the event where the egg cell fuses with the male gamete, spermatozoon. After the point of fertilization, the fused product of the female and male gamete is referred to as a zygote or fertilized egg. The fusion of male and female gametes usually occurs following the act of sexual intercourse. Pregnancy

neg: European nightcrawler a hermaphrodite, it has both male and female reproductive organs. In mating, the less strong partner is forced in to the female role which is more expensive in terms of biological reproduction costs, for a sperm cell is generally less massive and energy-demanding than an ovum ("egg cell"), which is the female reproductive cell (gamete) in anisogamous organisms. Two worms join clitella, the large, lighter-colored bands which contain the worms' reproductive organs, and which are only prominent during the reproduction process. The two worms exchange sperm. Both worms may secrete cocoons which contain an egg each. These cocoons are lemon-shaped

neg: Raillietina in each proglottid. "Raillietina" require two different hosts for a complete life cycle. The definitive hosts are mostly wild and domestic birds, and sometimes humans. The intermediate hosts are insects, such as ants and beetles. Mature eggs are released from the avian host through feaces by detaching the last gravid proglottid. The number of egg cell in each egg capsule is an identifying feature of each species. Eggs develop into larval forms called oncospheres, which are ingested by ants, and enters the alimentary canal, from where they migrates into the abdominal cavity of the insect and develops into mature cysticercoids.

neg: Morphokinetics IVF derived from the egg and the sperm cell respectively and two tiny cells called polar bodies. 2. Cleavage This begins when the zygote divides into two cells via mitosis. The division continues such that each cell divides into another two cells, which results in a multiplying effect. 3. Morula The ball of cells formed after the multiple divisions is called a morula. It consists of about 16-32 cells in a ball within a translucent, elastic layer called the zona pellucida. It will then undergo compaction which is a process where the cells bind firmly together and continue to develop into

neg: Craniopagus parasiticus monozygotic twins start to develop as an embryo, but the embryo fails to completely split. When this happens, one embryo will dominate development, while the other's development is severely altered. The key difference between a parasitic twin and conjoined twins is that in parasitic twins, one twin, the parasite, stops development during gestation, whereas the other twin, the autosite, develops completely. In normal monozygotic twin development, one egg is fertilized by a single sperm. The egg will then completely split into two, normally at the two-cell stage. If the egg splits in the early blastocyst stage, two inner cell masses

neg: Priochilus captivum provision each cell in the nest. In Brazil, a species of jumping spider (Salticidae) is often used. The spider is captured and stung, then laid on the ground while the female completes the cell. The mud takes about two hours to dry, and then the spider is placed inside, an egg is laid on its abdomen and the cell is sealed. The egg soon hatches and the wasp larva grows fast. By day five it has finished eating the abdomen of its spider host and by day nine it forms a cocoon. Males emerge through the seals of the cells

neg: Megaspore "Tridax trilobata", "Ehretia laevis", and "Alectra thomsoni", can undergo different patterns of megasporogenesis and therefore different patterns of megagametogenesis. If the monosporic pattern occurred, the single nucleus undergoes mitosis three times, producing an eight-nucleate cell. These eight nuclei are arranged into two groups of four. These groups both send a nucleus to the center of the cell; these become the polar nuclei. Depending on the species, these nuclei fuse together before or upon fertilization of the central cell. The three nuclei at the end of the cell near the micropylar become the egg apparatus, with an egg cell in the

neg: Tetragonisca angustula the provisioning and oviposition process, shortened to “POP”. Before oviposition occurs, workers fill the cells in the hive with food. Once the egg is placed in the cell, it is covered and not tended to again. So, any differences among bees during their initial development must come from differences in the environment within their cells. The size of the cells and the amount of food in each cell is the main determining factor in the size and role of the bee that develops in the cell. Therefore, "T. angustula" workers fulfill their biggest role before an egg is even placed

neg: Hypoblast and colleagues, at the distal tip of the mouse egg cylinder, thus this domain was called distal visceral domain (DVE). The DVE cells will move unilaterally to the future anterior until reaching the embryonic/ extra embryonic boundary and at this point, the DVE cells are also named as anterior visceral endoderm (AVE). This migration has been proved to be essential for establishing anteroposterior axis. Besides the AVE, another cell population appears to be separated at the posterior edge of the embryonic egg cylinder, referred to as posterior visceral endoderm (PVE). However, the function of this cell population was not as