Anatomy & Physiology

Anatomy & Physiology Study Guide • The descent of the testes through the inguinal canals occurs during fetal development. The testes remain connected to internal structures via the spermatic cords. The raphe marks the boundary between the two chambers in the scrotum. • The dartos muscle tightens the scrotum, giving it a wrinkled appearance as it elevates the testes; the cremaster muscles are more substantial muscles that pull the testes close to the body. • The tunica albuginea surrounds each testis. Septa extend from the tunica albuginea to the region of the testis closest to the entrance to the epididymis, creating a series of lobules. • Seminiferous tubules within each lobule are the sites of sperm production. From there, spermatozoa pass through the rete testis. Efferent ductules connect the rete testis to the epididymis. Between the seminiferous tubules are interstitial cells, which secrete sex hormones. • Seminiferous tubules contain spermatogonia, stem cells involved in spermatogenesis (the production of spermatozoa), and nurse (sustentacular) cells, which sustain and promote the development of spermatozoa. Oogenesis occurs in the ovaries, and hormones from the pituitary gland and gonads control female reproductive functions: • Key organs of the female reproductive system include the ovaries, uterine tubes, uterus, vagina, and external genitalia. • The ovaries, uterine tubes, and uterus are enclosed within the broad ligament. The mesovarium supports and stabilizes each ovary. • The ovaries are held in position by the ovarian ligament and the infundibulopelvic ligament. Major blood vessels enter the ovary at the ovarian hilum. Each ovary is covered by a tunica albuginea. • Oogenesis (ovum production) occurs monthly in ovarian follicles as part of the ovarian cycle, which is divided into a follicular (preovulatory) phase and a luteal (postovulatory) phase. • As follicle development proceeds, primary, secondary, and tertiary follicles are produced in turn. At ovulation, a secondary oocyte and the attached follicular cells of the corona radiata are released through the ruptured ovarian wall. The follicular cells remaining within the ovary form the corpus luteum, which later degenerates into scar tissue called a corpus albicans. • Each uterine tube has an infundibulumwith fimbriae (fingerlike projections), an ampulla, and an isthmus. Each uterine tube opens into the uterine cavity. For fertilization to occur, a secondary oocyte must encounter spermatozoa during the first 12–24 hours of its passage from the infundibulum to the uterus. • Peg cells lining the uterine tube secrete a fluid that completes the capacitation of spermatozoa. • The uterus provides mechanical protection, nutritional support, and waste removal for the developing embryo. Normally, the uterus bends anteriorly near its base (anteflexion). It is stabilized by the broad ligament, uterosacral ligaments, round ligaments, and lateral ligaments.

©2018

Achieve Page 351

of 368