When human oocytes complete meiosis
When does a human secondary oocyte complete meiosis II?
Answer D: explanation for every choice
A
Before birth, primary oocytes enter meiosis I and arrest in prophase I.
B
At ovulation, the oocyte has completed meiosis I and is arrested in metaphase II.
C
Puberty starts the monthly cycles in which meiosis I is completed.
D
Correct. The secondary oocyte is arrested in metaphase II and completes meiosis only if a sperm fertilizes it.
TakeawayProphase I arrest until ovulation. Metaphase II arrest until fertilization.
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Reviewed 2026-11-05 by a medical student. Spot an error? Report it with question ID bb138.