Which hormone produced by the ovaries plays a role in the oestrous cycle?

The hormone produced by the ovaries that plays a critical role in the oestrous cycle is oestrogen. This hormone is primarily involved in the regulation of the reproductive cycle in female mammals, particularly influencing the development and maturation of follicles in the ovaries. Oestrogen facilitates the growth and maintenance of reproductive tissues and promotes behaviors associated with estrus, which is when the female is receptive to mating.

During the follicular phase of the oestrous cycle, increased levels of oestrogen prepare the body for potential pregnancy by stimulating the growth of the uterine lining and other reproductive organs. This hormone also plays a role in signaling the onset of ovulation.

While progesterone, another ovarian hormone, also plays a role in the oestrous cycle by maintaining pregnancy and regulating other reproductive processes during the luteal phase, oestrogen is key during the earlier phases, specifically influencing the development and release of the eggs.

Insulin and oxytocin, while important hormones in other physiological processes, do not primarily regulate the oestrous cycle directly. Insulin is crucial for glucose metabolism and energy regulation, and oxytocin is associated with childbirth and lactation rather than the oestrous cycle itself.