Anatomy & Physiology

Anatomy & Physiology Study Guide The female reproductive system produces sex hormones and functional gametes. It also has the ability to support a developing embryo, protect the fetus, and nourish a newborn infant. The principal organs of the female reproductive system are the ovaries, the uterus, uterine tubes, the vagina, and the external genitalia. The ovaries, uterine tubes, and uterus are enclosed within an extensive mesentery known as the broad ligament . The uterine tubes run along the superior border of the broad ligament and open into the pelvic cavity lateral to the ovaries. The position of each ovary is stabilized and supported by the mesovarium. The broad ligament attaches to the sides and floor of the pelvic cavity, where it becomes continuous with the parietal peritoneum. This part of the peritoneal cavity is subdivided by the broad ligament. The pocket formed between the posterior wall of the uterus and the anterior surface of the colon is the rectouterine pouch ; the pocket formed between the uterus and the posterior wall of the bladder is the vesicouterine pouch. The Ovaries The small almond-shaped organs near the lateral walls of the pelvic cavity are the paired ovaries. The ovaries perform three main functions: production of immature female gametes, or oocytes; secretion of female sex hormones, including estrogens and progestins; and secretion of inhibin, involved in the feedback control of pituitary FSH production. The position of each ovary is stabilized by the mesovarium and by a pair of supporting ligaments: the ovarian ligament and the infundibulopelvic (suspensory) ligament. The infundibulopelvic ligament contains the major blood vessels of the ovary: the ovarian artery and ovarian vein. The interior tissues, or stroma, of the ovary can be divided into a superficial cortex and a deeper medulla. Gametes are produced in the cortex. Oogenesis Ovum production, or oogenesis, begins before birth, accelerates at puberty, and ends at menopause. Between puberty and menopause, oogenesis occurs on a monthly basis as part of the ovarian cycle. Unlike spermatogonia, the oogonia or stem cells of females, complete their mitotic divisions before birth. Between the third and seventh months of fetal development, the daughter cells, or primary oocytes, prepare to undergo meiosis. Continuation as far as the prophase of meiosis I occurs, but then the process stops. The primary oocytes remain in a state of suspended development until the individual reaches puberty. At which point, rising levels of FSH stimulate the commencing of the ovarian cycle. Each month thereafter, some of the primary oocytes are triggered to undergo further development. Most primary oocytes produced do not survive to puberty. The ovaries have roughly two million primordial follicles at birth, each containing a primary oocyte. Primordial follicles exist at the earliest stages of development. The population has dropped to about 400,000 by puberty. The rest of the primordial follicles degenerate in a process called atresia .

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