At which point does meiosis II complete?

Meiosis II is a pivotal process that completes the formation of gametes, specifically in females, where it occurs within the ovarian follicles. This phase is initiated but not completed until fertilization occurs. At ovulation, the oocyte is released and is typically arrested in metaphase II, meaning it has not yet completed meiosis II.

Once fertilization takes place, the sperm entry into the oocyte triggers the completion of meiosis II. This leads to the division of the secondary oocyte into a mature ovum and the second polar body, finalizing the meiotic division. Therefore, the completion of meiosis II aligns specifically with the event of fertilization, when the egg is stimulated to finish this final step of gametogenesis.