Anatomy and Physiology II Practice Test

What ovarian hormone reaches its highest concentration during the proliferative phase?

1. Progesterone

2. FSH

3. Estrogen

4. LH

The correct answer is: Estrogen

During the proliferative phase of the menstrual cycle, the ovarian hormone that reaches its highest concentration is estrogen. This phase occurs after menstruation and before ovulation, typically lasting from days 6 to 14 of a 28-day cycle. As the follicles in the ovaries mature, they produce increasing amounts of estrogen, primarily estradiol, which plays a crucial role in rebuilding and thickening the endometrial lining of the uterus in preparation for potential implantation of a fertilized egg. The rising levels of estrogen also exert feedback on the hypothalamus and pituitary gland, promoting a surge in luteinizing hormone (LH) that ultimately leads to ovulation. While the other hormones listed have important roles in the menstrual cycle, they do not reach peak levels during the proliferative phase in the same way that estrogen does. Progesterone, for instance, is primarily secreted during the luteal phase after ovulation. Follicle-Stimulating Hormone (FSH) is important for follicle development but does not peak during the proliferative phase; its levels are more elevated in the early part of the cycle. Luteinizing Hormone (LH) peaks at the time of ovulation, marking the transition from the