Fundamentals of Anatomy and Physiology

458 Chapter 19

Basement membrane

Sertoli cell

Sertoli

cell nucleus

Sperm cell

Spermatogonia

(stem cells)^

2n (^)
(^) MITOSIS (^)
Daughter cell 2n^
Primary spermatocyte 2n
MEIOSIS I
Secondary n n
spermatocytes
MEIOSIS II
Early n n n n
spermatids
Late n n n n
spermatids
Lumen of (^)
seminiferous (^)
tubule^ n n
n n (^)
(^) Sperm cell (^)
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Figure 19- 3 The process of spermatogenesis, which occurs in a seminiferous
tubule.
typical of males with more bulk and firmness in their
muscular physique. Testosterone stimulates maturation of
sperm cells. It causes enlargement of the thyroid cartilage,
resulting in the visible Adam’s apple in males, and the
deepening of the voice with its low range of pitch due to
thick vocal cords. Other secondary male sex characteristics
are also influenced by the production of testosterone. These
include aggressive behavior and body hair patterns. Body
hair patterns include the development of chest hair and
axillary hair within hereditary limits, facial hair, and
temporal hairline recession.
The Ducts of the System
As the sperm cells are formed (see Figure 19-2), they are
moved from the convoluted seminiferous tubules in the
testis to the straight tubules at the tip of each lobule.
Here the convoluted seminiferous tubules become linear
and lose their convolutions. These lead to a network of
ducts in the testis called the rete (REE-tee) testis. The
sperm are now transferred out of the testis through a series
of coiled efferent ducts that empty into a single tube
known as the ductus epididymis.