Meiosis in Females: Location and Process in the Human Reproductive System

In human females, meiosis occurs in the primary oocytes within the ovaries. The process comprises two consecutive meiotic divisions: meiosis I and meiosis II.

Meiosis starts in primary oocytes during embryonic development but gets arrested in prophase I until puberty. Once a female reaches sexual maturity, hormonal signaling induces a group of selected primary oocytes to resume meiosis I, culminating in the production of a single secondary oocyte and a much smaller polar body.

Subsequently, shortly before ovulation, the secondary oocyte initiates meiosis II but pauses again until fertilization by the sperm. Once the sperm penetrates the secondary oocyte during fertilization, it triggers the completion of meiosis II, splitting the haploid secondary oocyte into the mature ovum and another polar body.

Thus, while meiosis commences early during fetal development, the actual completion of both meiotic divisions and the formation of mature egg cells ready for fertilization takes place in the mature ovarian follicle's female reproductive system, near the time of ovulation.