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The egg cell or ovum (pl.: ova) is the female reproductive cell, or gamete, [1] in most anisogamous organisms (organisms that reproduce sexually with a larger, female gamete and a smaller, male one). The term is used when the female gamete is not capable of movement (non- motile ).
The megaspore that remains divides mitotically and develops into the gametophyte, which eventually produces one egg cell. [2] In the most common type of megagametophyte development in flowering plants (the Polygonum type), three mitotic divisions are involved in producing the gametophyte, which has seven cells, one of which (the central cell ...
An oocyte (/ ˈ oʊ ə s aɪ t /, oöcyte, or ovocyte is a female gametocyte or germ cell involved in reproduction. In other words, it is an immature ovum, or egg cell. An oocyte is produced in a female fetus in the ovary during female gametogenesis. The female germ cells produce a primordial germ cell (PGC), which then undergoes mitosis ...
The blastocyst has a diameter of about 0.1–0.2 mm and comprises 100-200 cells following 7-8 rounds of cleavage (cell division without cell growth). About seven days after fertilization, [ 6 ] the blastocyst undergoes implantation , embedding into the endometrium of the uterine wall where it will undergo further developmental processes ...
In the brown alga Fucus, all four egg cells survive oogenesis, which is an exception to the rule that generally only one product of female meiosis survives to maturity. In plants, oogenesis occurs inside the female gametophyte via mitosis. In many plants such as bryophytes, ferns, and gymnosperms, egg cells are formed in archegonia.
In amphibians, the development of the animal-vegetal axis occurs prior to fertilization. [1] Sperm entry can occur anywhere in the animal hemisphere. [2] The point of sperm entry defines the dorso-ventral axis - cells opposite the region of sperm entry will eventually form the dorsal portion of the body. [1] [3]
The yolk sac is a membranous sac attached to an embryo, formed by cells of the hypoblast layer of the bilaminar embryonic disc. This is alternatively called the umbilical vesicle by the Terminologia Embryologica (TE), though yolk sac is far more widely used. The yolk sac is one of the fetal membranes and is important in early embryonic blood ...
Parietal epithelial cell (PEC) Podocyte; Angioblast → Endothelial cell; Mesangial cell. Intraglomerular; Extraglomerular; Juxtaglomerular cell; Macula densa cell; Stromal cell → Interstitial cell → Telocytes; Kidney proximal tubule brush border cell; Kidney distal tubule cell; Connecting tubule cells; α-intercalated cell; β-intercalated ...