_a_, Testicle; _b_, epididymis; _c_, vas deferens; _d_, spermatic
artery; _e_, vesicula seminalis reflected to show the body of the
prostate, _f_; _e′_, excretory ducts of vesiculæ; _g_,
bulbo-urethral (Cowper’s) gland; _h_, urinary bladder; _i_, urethral
muscle; _k_, bulbo-cavernosus muscle; _l_, penis; _l′_, sigmoid
flexure of penis; _l″_, spiral anterior part of penis, exposed by
slitting open prepuce; _m_, orifice of preputial pouch; _n_,
retractor penis muscle. (Ellenberger-Baum, Anat. d. Haustiere.)
]
It is to be noted that these accessory glands are very small in
animals which have been castrated early.
The =penis= resembles in general that of the ox. The sigmoid flexure is,
however, prescrotal. The anterior portion has no glans, and is spirally
twisted, especially in erection. The =urethral orifice= is slit-like and
is situated ventro-laterally, close to the pointed extremity. The penis
in the adult boar measures about 18 to 20 inches (ca. 45 to 50 cm.) in
length. Its muscles resemble those of the bull; the bulbo-cavernosus is
very strong but short.
The =prepuce= has a narrow orifice, around which there are a number of
stiff hairs. The cavity is partially divided by a circular fold into a
posterior narrow portion and a much wider anterior portion. The lining
membrane of the posterior part is papillated, and is in close contact
with the penis. In the dorsal wall of the wide part there is a circular
opening which leads into a cul-de-sac, the =preputial diverticulum=.
This pouch is ovoid in form (when distended), and varies greatly in size
in different subjects. It extends for the most part backward over the
narrow part of the prepuce. Its cavity is partially divided by a narrow
median septum. It contains usually decomposing urine and macerated
epithelium, which have a characteristic and very unpleasant odor.
Concrements have been found in it.
Oehmke found that a cast of the pouch in a Yorkshire boar weighing
about 500 pounds measured 9 cm. in length, 12½ cm. in breadth, and 6
cm. in height. The opening into the prepuce will admit two fingers in
the adult, but is ordinarily closed by folds of the lining membrane.
The sac is much smaller in animals which were castrated young, and the
opening is vertical and further back; in them it is often empty or
contains only a little clear urine. The pouch is covered by a layer of
striped muscle which is mainly derived from the homologue of the
protractor of the prepuce of ruminants.
The =urethra= has a very long pelvic portion (ca. 15 to 18 cm. long in
the adult); it is inclosed (with the pars disseminata of the prostate)
by a thick =urethral muscle=. There is a distinct =bulb= at the root of
the penis. The penile part is of small caliber, and is surrounded by
erectile tissue which, however, does not extend to the extremity of the
penis.