During which stage of the estrous cycle does ovulation occur?

The correct choice is associated with the stage of the estrous cycle known as estrus, during which ovulation occurs. In this phase, the female animal is receptive to mating, and the follicle on the ovary releases a mature egg, marking the moment of ovulation. This is crucial for reproduction, as it is the period when the female can conceive if mating occurs.

In contrast, proestrus is the stage leading up to estrus, characterized by the development of ovarian follicles but with no ovulation taking place. Mestrus is not a commonly recognized term within the context of the estrous cycle and may lead to confusion with the term metestrus, which follows estrus and typically involves the processes related to the post-ovulation phase, where the animal is no longer in the fertile stage. Finally, diestrus is a stage that follows metestrus, where the body prepares for either pregnancy or the return to proestrus if pregnancy does not occur, and there’s no ovulation happening in this phase.

Understanding these stages is crucial for managing breeding and reproductive health in laboratory animals.