What happens during the estrus stage of a female's reproductive cycle?

During the estrus stage of a female's reproductive cycle, ovulation occurs. This is the phase when a mature egg is released from an ovary, making the female receptive to mating and capable of conception. In many species, this period is characterized by specific behavioral and physiological changes that indicate fertility and readiness to breed.

The estrus phase is crucial in the reproductive cycle as it marks the optimal time for fertilization to take place, which leads to potential pregnancy if mating occurs. Understanding this stage is essential for effective breeding management in laboratory animals and ensures that animals are bred at the most appropriate times to maximize reproductive success.

The other options refer to different processes that do not occur during the estrus stage. Menstruation is a process that occurs in some species after the estrus phase if fertilization has not taken place. Implantation of eggs occurs only after fertilization and during pregnancy. Development of the fetus is a stage that follows fertilization and implantation, leading to gestation. Thus, the correct understanding is that ovulation is the key event happening during the estrus stage.