Problem 13 - Entrance Test

This question tests the understanding of the roles of the corpus luteum and its hormones in the menstrual cycle. * Corpus Luteum Formation: After ovulation, the ruptured follicle transforms into the corpus luteum under the influence of LH. * Corpus Luteum Function: The primary role of the corpus luteum is to secrete large amounts of progesterone and some estrogen. These hormones are crucial for: 1. Maintaining the uterine lining (endometrium): Progesterone makes the endometrium receptive for implantation and maintains its thickness, essential for sustaining a pregnancy. 2. Negative feedback: Progesterone and estrogen from the corpus luteum exert negative feedback on the hypothalamus (GnRH) and anterior pituitary (FSH, LH), preventing new follicular development. Let's analyze the consequences of a failing corpus luteum: * Immediate impact: If the corpus luteum fails, it cannot produce sufficient progesterone and estrogen. * Effect on endometrium: Without adequate progesterone, the uterine lining cannot be maintained. * Result: This causes the endometrium to break down, leading to early menstruation (if no pregnancy occurs). * Impact on pregnancy: If fertilization and implantation were to occur, the lack of progesterone would mean the uterine lining could not support the embryo, leading to early miscarriage (difficulty maintaining pregnancy). Let's evaluate the options: A. Absence of the LH surge, preventing ovulation: The question states ovulation has occurred (on day 14), so the LH surge must have already happened. This consequence is incorrect for after ovulation. B. Rapid drop in estrogen and progesterone, leading to early menstruation and difficulty maintaining pregnancy: This accurately describes the consequences. A failing corpus luteum cannot sustain estrogen and progesterone levels. The decline in these hormones triggers the breakdown of the endometrium and menstruation, and would make it impossible to maintain an early pregnancy. C. Persistent high levels of FSH, causing multiple follicular development: While low estrogen/progesterone would reduce negative feedback on FSH, leading to some increase, the immediate consequence of corpus luteum failure is related to the current cycle's outcome, not necessarily immediate multi-follicular development (which would take time). FSH might rise after menstruation has occurred. D. Sustained high levels of progesterone, delaying menstruation indefinitely: This is the opposite of what would happen. A failing corpus luteum would lead to low progesterone, which triggers, rather than delays, menstruation.