Which hormonal changes occur during diestrus?

During diestrus, the phase of the estrous cycle that follows heat (estrus) and occurs after ovulation, the primary change is an increase in progesterone levels. This phase is characterized by the presence of a functional corpus luteum that develops from the ruptured follicle. The corpus luteum secretes progesterone, which is essential for preparing the uterus for a potential pregnancy and maintaining any pregnancy that may occur.

Progesterone plays a critical role by promoting the thickening of the uterine lining, inhibiting further ovulation, and maintaining a favorable environment for embryo development. If fertilization does not occur, progesterone levels will eventually decrease, leading to the next estrous cycle.

In contrast, the other hormonal changes mentioned do not align with the events of diestrus. Estrogen levels typically peak during estrus and subsequently decline, luteinizing hormone (LH) levels decrease after ovulation as there is no further stimulation for ovulation, and follicle-stimulating hormone (FSH) levels also decrease as the feedback from high progesterone levels inhibits its release. Therefore, recognizing the increase in progesterone as the hallmark of diestrus is crucial for understanding reproductive physiology in animals.