CHAPTER 18
Male Reproductive System
349
Ductus
deferens
Ductus
epididymis
(tail)
Ductus
epididymis
(body)
Medastinum
Ductus epididymis
(head)
Testis
Ductuli
efferentes
Rete testis
Tubuli recti
Tubuli recti
Tunica vaginalis
Tunica albuginea
Septum
Seminiferous
tubule
A
Lumen of the
Lumen of the
seminiferous tubules
seminiferous tubules
Lumen of the
seminiferous tubules
Interstitial connective
Interstitial connective
tissue
tissue
Interstitial connective
tissue
Septum
Septum
Septum
Basement
Basement
membrane
membrane
Basement
membrane
Tubuli recti
Tubuli recti
Tubuli recti
Septum
Septum
Septum
B
Myoid
Myoid
cells
cells
Myoid
cells
Seminiferous
Seminiferous
tubule
tubule
Seminiferous
tubule
Seminiferous
S
e
m
in
ife
r
o
u
s
epithelium
e
p
ith
e
liu
m
Seminiferous
epithelium
Lumen
Lumen
Lumen
Fibroblast
Fibroblast
Fibroblast
Seminiferous
Seminiferous
tubule
tubule
Seminiferous
tubule
Basement
Basement
membrane
membrane
Basement
membrane
C
Figure 18-3A.
Overview of the testis.
Each
testis
is composed of many convoluted
seminiferous
tubules
. The anterior portion of the testis is covered by a closed
sac of peritoneum called the
tunica vaginalis
(mesothelial sac).
The
tunica albuginea
is a thick layer of capsule (dense connec-
tive tissue) that surrounds and divides the testis into small lob-
ules; the connective tissue continues at the posterior part and
becomes thicker and forms the vertically oriented connective
tissue mass called the
mediastinum
. The mediastinum contains
the
rete testis
, which consists of a labyrinth of small channels
that collect sperm from the
tubuli recti
. The
ductus epididymis
is a single long, highly convoluted duct that receives sperm
from the
ductuli efferentes
. The epididymis is divided into
three parts: the head, body, and tail. The tail of the epididymis
connects with the
ductus deferens
. The testes play important
roles in the production of sperm and secretion of testosterone
(sex hormone).
Testis
Figure 18-3B.
Seminiferous tubules of the testis.
H&E,
3
122
Seminiferous tubules
are the main functional components of
the testis. Each of the several hundred seminiferous tubules
in each testis is a highly coiled tubule lined by a stratiF
ed
germinal (seminiferous) epithelium
containing various stages of
spermatogenic cells
. The seminiferous epithelium is supported
by the basement membrane. Cross sections of some seminifer-
ous tubules and a connective tissue septum are shown here.
The
tubuli recti
(straight tubules) are located in the connec-
tive tissue septa. The connective tissue between neighboring
tubules, which contains small vessels and endocrine cells, is
called
interstitial connective tissue
.
Figure 18-3C.
Seminiferous tubule.
H&E,
3
281
This is an example of a single
seminiferous tubule
,
consisting
of germinal epithelium and its basement membrane. The
seminiferous tubule is surrounded by a very thin connective
tissue containing a few F broblasts. Another type of cell, the
myoid cell
, has the appearance of smooth muscle cells, with fl
at
and elongated nuclei. These cells surround the seminiferous
tubules and contract to help the movement of the testicu-
lar fl
uid in which the spermatozoa are suspended. Neigh-
boring seminiferous tubules are in close contact with one
another. The various stages of the spermatogenic cells include
spermatogonia, spermatocytes
(primary and secondary), and
spermatids
(early, intermediate, and late). They are present in six
different speciF c combinations of cell types that deF
ne the st ages
of the cycle of the seminiferous epithelium (±igs. 18-11A
to 18-13B).
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