Question

describe ovarian function

please be specific and type. thank you!

Answer 1

The ovaries are the female reproductive organs that produce ovum or egg each ovarian/menstrual cycle in humans. There are two ovaries located on either side of the uterus. They are in contact with their respective fallopian tubes, which are attached to the uterus. Follicles, fluid filled sacs are the structures in ovaries that develop the egg/oocytes to maturity. Each ovary has a fixed number of follicles during entire lifetime and thus, ovarian cycle will terminate in the women at a particular stage known as menopause. Only around 300000 follicles (primordial follicles) remain, which is estimated to be around 25% of the follicle pool at birth. The primordial follicle develops into the pre-antral and the antral follicle. The pre-antral follicle development takes place in ascend of gonadotropin hormones. These follicles have 3 stages- primary, secondary and tertiary follicles. One of the tertiary follicles is selected at each cycle for ovulation and is the dominant follicle or Graafian follicle.

The ovarian function involves the maturation of the follicle (folliculogenesis), ovulation and formation of corpus luteum. This entire cycle is called ovarian cycle and is dependent on FSH (follicle stimulating hormone) and LH (luteinizing hormone) hormones secreted by the pituitary gland in response to the gonadotropin releasing hormone, GnRH. The dominant follicle grows in response to FSH produced by the pituitary. The dominant follicle has theca cells enclosing the granulosa cell, which encloses the ovum. The granulosa cell produces estrogen in response to FSH. Estrogen is essential for development of endometrial cells during follicular phase of menstrual cycle. It also is required for growth of breast tissue and supports pregnancy. Production of estrogen will inhibit menstrual bleeding. As estrogen levels rise, GnRH induces LH secretion. LH peak will induce ovulation, which is release of the ova due to breakage of the follicle. The granulosa cells will remain attached to the ovum. However, the thecal cells of the follicle will then form the corpus luteum. Corpus luteum produces progesterone that induces differentiation of the endometrial cells during luteal phase of menstrual cycle. Progesterone also supports pregnancy. Corpus luteum regresses if there is no pregnancy. However, corpus luteum continues to produce progesterone if embryo implantation occurs.

Other hormones produced by ovaries, in addition to estrogen and progesterone are inhibit, relaxin and oxytocin. Inhibin is the hormone produced by granulosa cell which is required to inhibit production of FSH. Relaxin is produced by the corpus luteum at end of pregnancy. Relaxin is involved in parturition as it relaxes the cervix and pelvic ligaments. Oxytocin is the hormone produced by hypothalamus and secreted by pituitary. It induces uterine contraction during parturition and also helps in regression of corpus luteum. Thus, the ovary not only has important functions during normal menstrual cycle, but plays very essential roles during pregnancy. They produced eggs that are required for fertilization and also nurture the embryo during pregnancy and help in parturition. Decline in ovarian function leads to menopause and cessation of estrogen and progesterone production. Estrogen is required for bone development as it is involved in absorption of calcium. Loss of estrogen leads to osteoporosis. Estrogen is also required during breast enlargement during pregnancy. Progesterone is required for growth of mammary glands.