Chapter 28: The Reproductive System
Introduction to the Reproductive System, p. 1030
The reproductive system includes the following components:
, or reproductive organs that produce gametes
Ducts that receive and transport the gametes.
Accessory glands and organs that secrete fluids into the ducts of the reproductive system or into
other excretory ducts.
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
; the ejaculatory duct
; and the urethra
before leaving the body.
Accessory organs—the seminal vesicles
, the prostate gland
, and the bulbourethral glands
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.
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
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.
, one or both of the testes have not descended into the scrotum by the time of
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).
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