NEETZoologyHuman Reproduction
A healthy adult female misses her expected menstrual period. A subsequent blood test reveals persistently high levels of progesterone and estrogen. Based on this hormonal profile, which of the following events must have occurred regarding her gametes and ovarian structures during this cycle?
Options
- AThe secondary oocyte was not fertilized, but the Graafian follicle continues to secrete high levels of progest
- BThe corpus luteum degenerated into a corpus albicans, which is actively preventing the onset of menstruation.
- CThe secondary oocyte completed meiosis II upon fertilization, and the corpus luteum is actively maintained.
- DThe primary oocyte completed meiosis I to directly form a diploid ovum, maintaining the endometrial lining.
Correct answer
C. The secondary oocyte completed meiosis II upon fertilization, and the corpus luteum is actively maintained.
Step-by-step solution
Persistently high levels of progesterone and estrogen along with a missed menstrual period indicate that the corpus luteum has not degenerated. This occurs when a pregnancy is established. For pregnancy to occur, the secondary oocyte must have been fertilized by a sperm. The entry of the sperm induces the completion of the second meiotic division (meiosis II) in the secondary oocyte, resulting in the formation of a second polar body and a haploid ovum (ootid). If fertilization had not occurred, the corpus luteum wo