USA Biology Olympiad (USABO) Practice Exam

The corpus luteum plays a crucial role during early pregnancy primarily by secreting hormones, particularly progesterone and estrogen. After ovulation, the ruptured follicle transforms into the corpus luteum, which is essential for maintaining the early stages of a pregnancy. Progesterone is vital as it prepares the uterine lining for potential implantation of a fertilized egg, ensuring a suitable environment for the embryo. It also helps to suppress the maternal immune response to prevent rejection of the embryo.

While the other options refer to functions that are not characteristic of the corpus luteum, such as carbohydrate production or fat storage, the primary and significant constitutional function is hormone secretion, making it a pivotal structure in supporting early pregnancy until the placenta takes over hormone production later on. Thus, its role is intricately linked to sustaining early embryonic development and establishing pregnancy by providing the necessary hormonal support.