Question

During oogenesis 2nd meiotic division is :- (a) Completed after puberty (b) Completed just before puberty (c) Completed after ovulation (d) Completed before fertilization (e) Completed during maturation phase

Which of above statements are correct ?

• A. a, c & e
• B. b, c, d
• C. a, b & e
• D. a, d, e

Answer 1

Answer: (A)

(1) a, c & e

Answer 2

The question asks about the timing of the 2nd meiotic division during oogenesis. Let's analyze each statement:

• (a) Completed after puberty: Oogenesis begins before birth, but the primary oocytes arrest in prophase I. After puberty, under hormonal influence, one primary oocyte typically completes meiosis I each month, forming a secondary oocyte. This secondary oocyte is then ovulated. The completion of meiosis II occurs only upon fertilization, which happens after ovulation, and thus, after puberty. So, this statement is broadly correct.
• (b) Completed just before puberty: This is incorrect. The second meiotic division is arrested at metaphase II and only completes upon fertilization, which occurs well after puberty begins.
• (c) Completed after ovulation: During ovulation, a secondary oocyte (arrested in metaphase II) is released from the ovary. The second meiotic division is completed only if a sperm fertilizes this secondary oocyte. Therefore, it is completed after ovulation. This statement is correct.
• (d) Completed before fertilization: This is incorrect. The entry of the sperm into the secondary oocyte triggers the completion of the second meiotic division. So, it completes during or simultaneous with fertilization, not before it.
• (e) Completed during maturation phase: The meiotic divisions (Meiosis I and Meiosis II) are collectively referred to as the maturation divisions of the oocyte. The completion of the second meiotic division is indeed part of this maturation process. This statement is correct.

Based on the analysis, statements (a), (c), and (e) are correct.

Therefore, the correct combination of statements is (a), (c), and (e).