Oogenesis

Oogenesis
Dorlands /Elsevier	12339107
Anatomical terminology []

Oogenesis, ovogenesis, or oögenesis /ˌoʊ.əˈdʒɛnᵻsɪs/ is the differentiation of the ovum (egg cell) into a cell competent to further development when fertilized. It is developed from the primary oocyte by maturation.

In mammals, the first part of oogenesis starts in the germinal epithelium, which gives rise to the development of ovarian follicles, the functional unit of the ovary.

Oogenesis consists of several sub-processes: oocytogenesis, ootidogenesis, and finally maturation to form an ovum (oogenesis proper). Folliculogenesis is a separate sub-process that accompanies and supports all three oogenetic sub-processes.

Oogonium —(Oocytogenesis)—> Primary Oocyte —(Meiosis I)—> First Polar Body (Discarded afterward) + Secondary oocyte —(Meiosis II)—> Second Polar Body (Discarded afterward) + Ovum

It should be noted that oocyte meiosis, important to all animal life cycles yet unlike all other instances of animal cell division, occurs completely without the aid of spindle-coordinating centrosomes.

The creation of oogonia traditionally doesn't belong to oogenesis proper, but, instead, to the common process of gametogenesis, which, in the female human, begins with the processes of folliculogenesis, oocytogenesis, and ootidogenesis.

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