Question:medium
Completion of meiosis I (the first meiotic division of the germ cell) occurs in:
Completion of meiosis I (the first meiotic division of the germ cell) occurs in:
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The oocyte sits arrested for years and only finishes its first division around ovulation.
Updated On: Jun 23, 2026
- Adult ovary
- Prepubertal testis
- At birth in the ovary
- All of the above
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The Correct Option is A
Solution and Explanation
Timeline approach: the oocyte starts meiosis I before birth but freezes in prophase, and only finishes that first division around ovulation in the reproductive years, so the right site is the adult ovary.
Why not at birth (option 3): at delivery the primary oocyte is still locked in prophase I, so meiosis I is not complete at birth.
Why not prepubertal testis (option 2): in males, the meiotic divisions of spermatogenesis switch on only at puberty, so a prepubertal testis has no completed meiosis to offer.
Because options 2 and 3 are both wrong, the all-of-the-above option (option 4) also fails.
Supporting figures: the germ-cell pool peaks near 6-7 million at about 20 weeks of intrauterine life and drops to roughly 2 million primordial follicles by birth, all still arrested. Hence the completion of meiosis I happens in the adult ovary.
Why not at birth (option 3): at delivery the primary oocyte is still locked in prophase I, so meiosis I is not complete at birth.
Why not prepubertal testis (option 2): in males, the meiotic divisions of spermatogenesis switch on only at puberty, so a prepubertal testis has no completed meiosis to offer.
Because options 2 and 3 are both wrong, the all-of-the-above option (option 4) also fails.
Supporting figures: the germ-cell pool peaks near 6-7 million at about 20 weeks of intrauterine life and drops to roughly 2 million primordial follicles by birth, all still arrested. Hence the completion of meiosis I happens in the adult ovary.
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