Estrous and Menstrual Cycles

nal phase of the cycle. If fertilization has occurred, the corpus luteum continues to secrete progesterone, supporting the mucous membrane and preparing it to receive a fertilized egg.

The estrous and menstrual cycles are key processes ensuring the reproductive function of female mammals, including humans. Although these cycles manifest differently in different animal species, they are all based on changes in the levels of hormones such as estrogen, progesterone, follicle-stimulating hormone and luteinizing hormone, which regulate the growth and development of eggs, the lining of the uterus, changes in sexual desire and other processes.

The estrous cycle in animals, including cats, dogs and other domestic and wild animals, usually lasts from several days to several weeks, and is manifested by changes in the behavior and physiology of the animal, including an increase in sexual desire, changes in the lining of the vagina and uterus, and changes in the level of hormones.

In women and female great apes, the estrous cycle is replaced by the menstrual cycle, which manifests itself in the form of periodic bleeding. The menstrual cycle lasts approximately 28 days and consists of two phases: follicular and luteal. During the follicular phase, eggs and the lining of the uterus grow and estrogen is released. During ovulation, a mature egg is released from the ovary and moves to the uterus. During the luteal phase, the corpus luteum secretes progesterone to maintain the lining of the uterus for the potential implantation of a fertilized egg. If fertilization does not occur, the corpus luteum atrophies, progesterone levels decrease, and a new cycle begins with bleeding.

The estrous and menstrual cycles play an important role in the reproductive function of female mammals, and their disturbances can lead to various problems of the reproductive system. Understanding these cycles and their characteristics in different animal species and in women is important for the successful management of pregnancy and childbirth, as well as for the development of methods of birth control and treatment of reproductive diseases.