_a_, _a′_, Testicles; _b_, scrotum, opened and reflected; _c_, tunica
vaginalis communis, opened and reflected; _d_, ligament of
epididymis; _e_, tunica vaginalis propria (mesorchium); _f_, vas
deferens; _g_, _g′_, tail of epididymis; _h_, body of same; _i_,
head of same; _k_, digital fossa or sinus epididymidis; _l_,
spermatic vessels showing through tunica vaginalis propria; _m_,
spermatic artery; _n_, prepuce; _n′_, raphé; _o_, preputial orifice.
(After Ellenberger-Baum, Top. Anat. d. Pferdes.)
]
The =epididymis= is covered by the tunica vaginalis propria and a thin
albuginea. Its head consists of =lobules= (Lobuli epididymidis), each of
which consists of a coiled tubule or =conus vasculosus=, which succeeds
a vas efferens. By the union of these tubules is formed a single tube,
the =duct of the epididymis= (Ductus epididymidis), which, by its
complex coils, forms the body and tail of the epididymis and terminates
in the vas deferens. The tubules and the coils of the duct of the
epididymis are held together by connective tissue and unstriped
muscle-fibers. The tubules and duct are lined with ciliated epithelium,
and the duct has a muscular coat which consists of longitudinal and
circular fibers.
=Vessels and Nerves.=—The testicle is richly supplied with blood by the
=spermatic artery=, a branch of the posterior aorta. The artery descends
in the anterior part of the spermatic cord, and is very tortuous near
the testicle; on reaching the attached border of the gland it passes
backward in a flexuous manner, giving branches to the testicle and
epididymis, turns around the posterior extremity, and runs forward on
the free border to the anterior extremity. It is partially embedded in
the tunica albuginea, and detaches lateral branches which ascend in a
tortuous fashion on each surface of the testicle; these give off small
branches which enter the gland on the septa.
[Illustration:
FIG. 391.—RIGHT TESTICLE AND SPERMATIC CORD OF HORSE, INCLOSED IN
TUNICA VAGINALIS.
_c_, Tunica vaginalis communis; _g_, prominence caused by tail of
epididymis; _p_, cremaster externus muscle. (After Ellenberger-Baum,
Top. Anat. d. Pferdes.)
]
[Illustration: