Question

multiple choice question
during pregnancy, human chorionic gonadotropin hormone prevents the breakdown of the:
placenta
graafian follicle
corpus luteum
endometrium

Explanation:

After ovulation, the Graafian follicle transforms into the corpus luteum. The corpus luteum secretes progesterone which is essential for maintaining the endometrium (the lining of the uterus) during pregnancy. Human chorionic gonadotropin (hCG) is produced by the trophoblast cells of the developing embryo. hCG acts on the corpus luteum, preventing its degeneration. If the corpus luteum were to break down, progesterone levels would drop, and the endometrium would slough off, leading to the end of pregnancy. The placenta develops later in pregnancy and produces its own hormones (including hCG in later stages, but initially it's the embryo - derived trophoblast cells). The Graafian follicle is the pre - ovulatory structure. The endometrium is the target of progesterone (secreted by the corpus luteum) but is not directly prevented from breakdown by hCG (hCG acts on the corpus luteum which in turn acts on the endometrium).

Answer:

corpus luteum