The second maturation division of the mammalian ovum occurs
- Shortly after ovulation before the ovum makes entry into the Fallopian tube
- Until after the ovum has been penetrated by a sperm
- Until the nucleus of the sperm has fused with that of the ovum
- in the Graafian follicle following the first maturation division
Answer
(2) Until after the ovum has been penetrated by a sperm
Solution
The primary oocyte completes meiosis I inside the tertiary follicle and forms the secondary oocyte, which is released at ovulation.
As per NCERT, the entry of the sperm into the secondary oocyte induces the completion of its second meiotic division, forming the ovum (ootid) and a second polar body.
∴ The second maturation division is completed only after the sperm has penetrated the ovum, and before the sperm nucleus fuses with the ovum nucleus.
Answer: (2)