 Your students, in this topic we shall discuss the role of ovaries as endocrine tissue. Ovaries produce and release mainly two groups of female sex hormones. These are the progesterone and astrogens. Astrogens include astradiol, astrone and astryol. Ovaries also secrete two other hormones which are relaxing. This hormone is produced just prior to parturation or childbirth. The other hormone is inhibin which signals the pituitary to inhibit the release of follicle stimulating hormone. We shall discuss the role of progesterone and astrogen in detail. These hormones work together to promote the development of female secondary sexual characters. They also maintain the uterine and ovarian cycles and also help in fertility of the female. Dear students, we shall discuss in detail the role of these two hormones in the uterine and ovarian cycles which are actually two linked reproductive cycles in human females. The uterine cycle also called the menstrual cycle involves cyclic changes in the uterus. This cycle is completed in 28 days in human females. The menstrual cycle, ovarian cycle is running in ovaries and in ovaries cyclic events are taking place in which follicles are developing and the ovulation process is taking place. Dear students, these two cycles link the hormonal activity. These hormones, astrogen and progesterone, they synchronize the follicle growth and ovulation with the establishment of uterine lining. In this way, the follicle growth and ovulation are taking place in the ovary cycle. In this way, in the uterine cycle, the growth of the uterine lining occurs and this is synchronized with the progesterone or astrogens. Dear students, now we shall discuss that astrodiole is secreted during the ovary cycle which begins with the release of gonadotropin-releasing hormone from the hypothalamus. This gonadotropin-releasing hormone stimulates the pituitary to release FSH and LH. These two hormones are involved in the stimulation of follicle growth. When the follicles are growing, their thica-interna cells start to secrete astrodiole which is an astrochan. Dear students, the amount of astrodiole rises slowly during the follicular phase till the maturation of oocyte. Just prior to ovulation, estrogen levels are at their peak. These astrogens feed back positively to the pituitary and hypothalamus which result in producing a surge in the rise of FSH as well as LH. Dear students, the rise in FSH and LH accelerates the maturation and development of follicles. When follicle completes its maturation, then it ruptures. This stimulus of rupturing comes from leutinizing hormone. As a result, egg or ovum is released. Dear students, when ovulation has occurred, FSH stimulates the secretion of another hormone from the ovarian follicles that is called the inhibin hormone. This inhibin is produced by another type of cells in the follicle which are called granulosa cells. Its secretion reaches peak near the ovulation. It feeds back the anterior pituitary to suppress the release of follicle-stimulating hormone but it does not suppress the release of leutinizing hormone. Dear students, when the ovum is released, leutinizing hormone transforms the ruptured follicle into a temporary endocrine tissue which is called carpus leutium. This carpus leutium secretes astrogens and progesterone. This secretion causes decrease in the secretion of both FSH and LH. Dear students, the ovarian and uterine cycles are synchronized when the increasing astrogens concentration during the fall of the ovarian follicles is reduced. When the increasing astrogens concentration during the follicular phase simultaneously stimulates proliferation of the endometrium tissue and endometrium tissue lining of the uterus. As a result, the follicular phase develops astrogens or produces endometrium, which means the wall of the uterus becomes thicker. Later, progesterone plays another role in stimulating the secretion of the endometrial fluid which means the uterus is prepared for the implantation of fertilized ovum. But, if fertilization is not done, then carpus leutium degenerates in about 14 days. As a result, the secretion of astrogens and progesterone drops. However, if the egg is fertilized and is implanted, an active carpus leutium is maintained. So, astrogens and progesterone's secretion continues. Carpus leutium secretions of astrogens and progesterone until the placenta is fully developed and then the production of these hormones is taken into control. At this stage, carpus leutium degenerates. However, in many mammals, for example rats, carpus leutium degenerates, but it is stimulated by prolactin and continues to synthesize and secrete astrogens and progesterone throughout the gastrician period.