Question

Completion of meiosis I (the first meiotic division of the germ cell) occurs in:

• A. Adult ovary
• B. Prepubertal testis
• C. At birth in the ovary
• D. All of the above

Hint:

The oocyte sits arrested for years and only finishes its first division around ovulation.

Answer 1

The Correct Option is A

Step 1: In the female, oogonia enter meiosis in fetal life but the primary oocytes arrest in prophase of meiosis I. They stay arrested for years.
Step 2: Meiosis I is completed only after puberty, around the time of ovulation each cycle, that is, in the adult ovary. So option 1 is correct and option 3 (at birth) is wrong, because at birth the oocyte is still arrested.
Step 3: Numbers for context: about 6-7 million oocytes at 20 weeks of intrauterine life, falling to roughly 2 million primordial follicles at birth.
Step 4: In the male, spermatogenesis and its meiotic divisions begin only at puberty, so they do not occur in the prepubertal testis, making option 2 wrong.
So the answer is adult ovary.