Which structure is responsible for maintaining estrogen and progesterone secretion during early pregnancy?

The corpus luteum is the correct structure responsible for maintaining estrogen and progesterone secretion during early pregnancy. After ovulation, the remnants of the ovarian follicle transform into the corpus luteum, which plays a crucial role in producing these hormones.

During the first trimester of pregnancy, the hormones released by the corpus luteum are essential for maintaining the uterine lining, providing the appropriate environment for the developing embryo. Progesterone, in particular, helps to prevent menstruation and supports the maintenance of the early pregnancy until the placenta takes over hormone production later on.

In the context of the other options: the corpus albicans represents the degenerated form of the corpus luteum and does not produce hormones; ovarian follicles are involved in the maturation of eggs and hormone production prior to ovulation, but they do not maintain hormone secretion during pregnancy; and the Graafian follicle is a mature ovarian follicle that releases the egg during ovulation, after which it transforms into the corpus luteum. Thus, none of these structures fulfill the role of maintaining estrogen and progesterone secretion during the early stages of pregnancy like the corpus luteum does.