Q. The second maturation division of the mammalian ovum occurs :
(a) In the Graafian follicle following the first maturation division.
(b) Shortly after mutation before the ovum makes entry into the Fallopian tube.
(c) After the ovum has been penetrated by a sperm
(d) After the nucleus of the sperm has fused with that of the ovum.
Solution :
Correct option : C During oogenesis, primary oocyte grows and completes meiosis I (first maturation division) producing a large secondary oocyte and a small polar body. The secondary oocyte proceeds with meiosis II (second maturation division) but the division gets arrested at metaphase stage. It is in this stage of oocyte that the ovum is shed during ovulation. It passes into oviduct, where the cell cycle resumes only after the entry of sperm. So, the correct answer is ‘ After the ovum has been penetrated by a sperm’.
