If fertilization does not occur, what will happen to the oocyte in a typical human menstrual cycle?

• A. It will remain dormant in the ovary until the next cycle.
• B. It will degenerate and be reabsorbed or expelled during menstruation.
• C. It will fuse with a polar body to form a zygote.
• D. It will continue to divide and develop into an embryo.

Answer: (B)

Verified step by step guidance

1. Step 1: Understand the context of the problem. The question is asking about the fate of the oocyte (egg cell) in a typical human menstrual cycle if fertilization does not occur. Fertilization refers to the fusion of a sperm cell with an oocyte to form a zygote.
2. Step 2: Recall the biological process of the menstrual cycle. In humans, the menstrual cycle involves the release of an oocyte during ovulation. If fertilization does not occur, the oocyte does not develop further into an embryo.
3. Step 3: Clarify the options provided. The first option suggests the oocyte remains dormant in the ovary, which is incorrect because the oocyte is released during ovulation and does not return to the ovary. The second option states the oocyte degenerates and is reabsorbed or expelled during menstruation, which aligns with the biological process. The third option suggests the oocyte fuses with a polar body to form a zygote, which is incorrect because fertilization involves a sperm cell, not a polar body. The fourth option suggests the oocyte continues to divide and develop into an embryo, which only happens if fertilization occurs.
4. Step 4: Focus on the correct biological process. If fertilization does not occur, the oocyte undergoes a process called atresia, where it degenerates. The remnants of the oocyte are either reabsorbed by the body or expelled during menstruation along with the uterine lining.
5. Step 5: Conclude that the correct answer is: 'It will degenerate and be reabsorbed or expelled during menstruation,' as this is consistent with the biological events of the menstrual cycle when fertilization does not occur.