Reproduction Outline

Reproduction Outline - Chapter 28: The Reproductive System...

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Chapter 28: The Reproductive System Introduction to the Reproductive System, p. 1030 The reproductive system includes the following components: o Gonads , or reproductive organs that produce gametes and hormones. o Ducts that receive and transport the gametes. o Accessory glands and organs that secrete fluids into the ducts of the reproductive system or into other excretory ducts. o Perineal structures that are collectively known as the external genitalia . The Reproductive System of the Male, p. 1030 Proceeding from a testis, the spermatozoa travel within the epididymis ; the ductus deferens , or vas deferens ; the ejaculatory duct ; and the urethra before leaving the body. Accessory organs—the seminal vesicles , the prostate gland , and the bulbourethral glands — secrete various fluids into the ejaculatory ducts and urethra. The external genitalia consist of the scrotum , which encloses the testes, and the penis , an erectile organ through which the distal portion of the urethra passes. The Testes Each testis has the shape of a flattened egg that is roughly 5 cm (2 in.) long, 3 cm (1.2 in.) wide, and 2.5 cm (1 in.) thick. Each has a weight of 10–15 g (0.35–0.53 oz). The testes hang within the scrotum, a fleshy pouch suspended inferior to the perineum, anterior to the anus and posterior to the base of the penis. Descent of the Testes During development of the fetus, the testes form inside the body cavity adjacent to the kidneys. A bundle of connectivetissue fibers—called the gubernaculum testis —extends from each testis to the posterior wall of a small anterior and inferior pocket of the peritoneum. As the fetus grows, the gubernacula do not get any longer, so they lock the testes in position. o In cryptorchidism , one or both of the testes have not descended into the scrotum by the time of birth. The Spermatic Cords The spermatic cords are paired structures extending between the abdominopelvic cavity and the testes. Each spermatic cord consists of layers of fascia and muscle enclosing the ductus deferens and the blood vessels, nerves, and lymphatic vessels that supply the testes. The blood vessels include the deferential artery , a testicular artery , and the pampiniform plexus of a testicular vein. Branches of the genitofemoral nerve from the lumbar plexus provide innervation. Each spermatic cord begins at the entrance to the inguinal canal (a passageway through the abdominal musculature). After passing through the inguinal canal, the spermatic cord descends into the scrotum. The inguinal canals form during development as the testes descend into the scrotum; at that time, these canals link the scrotal cavities with the peritoneal cavity. In normal adult males, the inguinal canals are closed, but the presence of the spermatic cords creates
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This note was uploaded on 12/29/2011 for the course BIOLOGY 24011 taught by Professor Pan during the Fall '11 term at HCCS.

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Reproduction Outline - Chapter 28: The Reproductive System...

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