Primary oocyte

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noun, plural: primary oocytes

The oocyte that arises from the oogonium via the process of oocytogenesis, and gives rise to secondary oocyte and polar body after first meiotic division (meiosis I).


In humans, the primary oocytes are produced by the process of oocytogenesis that occurs during embryonic stage. At that time each oogonium inside the ovaries of the fetus divides and enters the initial stage of meiosis I to become the primary oocyte.

The primary oocyte however will not complete meiosis I but rather stopped at prophase I of meiosis I. It will only complete meiosis at the time of ovulation (that is at the time the child reaches the puberty stage). By that time, the primary oocyte undergoes first meiotic division giving rise to one secondary ooctye and one polar body.

See also: secondary oocyte