362
UNIT 3
Organ Systems
Extratesticular Genital Ducts
Ductus
deferens
Ductus
epididymis
(tail)
Ductus
epididymis
(body)
Ductus epididymis
(head)
Seminiferous
tubule
Mediastinum
Mediastinum
Mediastinum
Seminiferous
Seminiferous
tubule
tubule
Seminiferous
tubule
Lumen of ductus epididymis
Epithelium
Connective tissue (lamina propria)
Smooth muscle
Figure 18-16.
Ductus epididymis.
H&E,
3
11; inset
3
75
This is an example of the
ductus epididymis
in the head region. The ductus epididymis is a single highly convoluted tube about 4 to 5 m
in length. It connects the
ductuli efferentes
to the
ductus deferens
. The ductus epididymis is lined by pseudostratiF ed columnar epithelium
with long stereocilia and is supported by connective tissue (lamina propria) and a circular smooth muscle layer in its wall. The ductus
epididymis can be divided into three regions:
head
,
body
, and
tail
. The
head
of the ductus epididymis, also called the
initial region
,
receives spermatozoa from the ductuli efferentes. The spermatozoa in the head of ductus epididymis are weak and unable to function
effectively in fertilization. They pass through the
body
region with the help of contraction of the smooth muscle in the wall of the
ductus epididymis and are stored in the
tail
region, where the spermatozoa undergo maturation. The maturation of the spermatozoa
is infl uenced by androgenic hormones. The F nal step of maturation is called
capacitation
and occurs only after the spermatozoa
enter the female reproductive tract. Capacitation enables sperm to penetrate and fertilize an egg.
Epididymitis
is an infl ammation of the epididymis. Common causes include
Chlamydia trachomatis
,
Escherichia coli
, and
Neisseria
gonorrhoeae
infections. In the male,
urethritis
(an infl ammation of the urethra) is often associated with epididymitis. Chronic
epididymitis may result in infertility, because spermatozoa are stored and mature in the tail of the ductus epididymis.
D. Cui
Seminiferous
tubules
Ductus
epididymis
Seminal
vesicle
Prostate
gland
Bulbourethral
gland
Penile
urethra
Ductus
deferens
Urethra
Ejaculatory
ducts
Rete
testis
Tubuli
recti
Urethral
orifice
Ductuli
efferentes
Intratesticular
genital ducts
Extratesticular
genital ducts
Penis
Accessory
genital glands
Pathway for Sperm Conduction through the Genital Ducts
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