Question

The second maturation division of the mammalian ovum occurs

• A. shortly after ovulation before the ovum makes entry into the Fallopian tube
• B. until after the ovum has been penetrated by a sperm
• C. until the nucleus of the sperm has fused with that of the ovum
• D. in the Graafian follicle following the first maturation division

Answer 1

Answer: (B)

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.