CHAPTER 18
Male Reproductive System
363
Figure 18-17A.
Epithelium of the ductus epidi-
dymis.
H&E,
3
305
The
epithelium of the
ductus epididymis
is a
pseudostrati±
ed columnar epithelium
composed of
basal cells
and
principal cells
. The
basal cells
are short
with round nuclei; they are stem cells and are capable
of differentiating into principal cells. The
principal
cells
are columnar cells with elongated nuclei and
apical stereocilia (long microvilli, 10
μ
m or more in
length, which function in absorption but have no
motile function). They absorb large volumes of tes-
ticular fl
uid. The principal cells also play an impor-
tant role in the secretion of glycerophosphocholine,
which inhibits
capacitation
of the premature sperm
in the male reproductive tract. Normally, capacita-
tion
happens only after the sperm enters the female
reproductive tract.
Fig. 18-17B
Stereocilia
Pseudostratified
columnar epithelium
Basement
Basement
membrane
membrane
Basement
membrane
Connective
Connective
tissue
tissue
Connective
tissue
A
Head of spermatozoan
Tail of spermatozoan
Middle piece of
spermatozoan
Stereocilia
Junctional complex
B
Figure 18-17B.
Epithelium of the ductus epididymis.
EM,
3
5,900
The view here is limited to part of the lumen and the apical ends of the columnar epithelial cells forming the wall of the
ductus
epididymis. Junctional complexes
between neighboring epithelial cells seal the contents of the lumen from the interstitial compart-
ment underlying the epithelium. The extremely long microvilli (
stereocilia
) are a refl
ection of the large amount of testicular fl
uid
that is resorbed by the ductus epididymis. The lumen is the site of storage and F
nal maturation of the spermatozoa that have been
delivered to the epididymis by the fl ow of the testicular fl
uid. Note the randomly oriented sections through the
heads
,
middle pieces
,
and
tails
of
spermatozoa
in the lumen.
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