An oocyte, ovocyte, or rarely o÷cyte, is a female gametocyte or germ cell involved in reproduction. In other words, it is an immature ovum. An oocyte is part of the ovary development. The germ cells produce a primordial germ cell (PGC) which becomes an oogonia which marks the start of mitosis. After mitosis stops (due to actions of retinoic acid and the mesenephros) meiosis starts. This stage the oogonia is now an Oocyte (pronounced ''oh'a (like Noah)-site'').
The formation of an oocyte is called oocytogenesis, which is a part of oogenesis. Oogenesis results in the formation of both primary oocytes before birth, and of secondary oocytes after it as part of ovulation.
|Cell type||ploidy/chromosomes||chromatids||Process||Time of completion|
|Oogonium||diploid/46||2N||Oocytogenesis (mitosis)||third trimester|
|primary Oocyte||diploid/46||4N||Ootidogenesis (meiosis 1) (Folliculogenesis)||Dictyate in prophase I until ovulation|
|secondary Oocyte||haploid/23||2N||Ootidogenesis (meiosis 2)||Halted in metaphase II until fertilization|
|Ootid||haploid/23||1N||?||Minutes after fertilization|
Oocytes are rich in cytoplasm which contains yolk granules to nourish the cell early in development.
During the primary oocyte stage of oogenesis, the nucleus is called a germinal vesicle The only normal type of secondary oocyte has sex chromosomes 23,X (where sperm can be 23,X or 23,Y).
The space wherein an ovum or immature ovum is located is the cell-nest.
William K. Purves, Gordon H. Orians, David Sadava, H. Craig Heller, Craig Heller (2003). Life: The Science of Biology(7th ed.), pp. 823–824
This article is based on "Oocyte" from the free encyclopedia Wikipedia (http://en.wikipedia.org). It is licensed under the terms of the GNU Free Documentation Licencse. In the Wikipedia you can find a list of the authors by visiting the following address: http://en.wikipedia.org/w/index.php?title=Oocyte&action=history