The right vesicula is sectioned frontally. The dotted line indicates
the backward extension of the peritoneum.
]
The spermatic cords emerge through the outer angles of the external
inguinal rings, and curve downward and inward to the neck of the
scrotum. The external rings are about four inches (ca. 10 cm.) long,
and are two and a half to three inches (6 to 8 cm.) apart. In animals
in good condition there is a large mass of fat above the neck of the
scrotum, between the spermatic cords. The mesorchium extends to the
bottom of the tunica vaginalis forming a narrow fold (ca. 1 cm. wide)
which attaches the epididymis to the posterior part of the tunic.
The inguinal canal presents several special features in the bull. The
internal ring is very long. Its anterior border, formed by the edge of
the internal oblique, is decidedly concave and is tendinous in its
inner part. The long axis of the external ring is directed outward,
forward, and downward. The spermatic cord lies in its outer part, the
external pudic vessels in its middle. A muscular band about an inch
wide, detached from the internal oblique muscle, crosses the outer
side of the vaginal ring.
The =vas deferens= is small in caliber. The urogenital fold is narrow,
so that the vasa are closer together in it than in the horse. On
reaching the posterior part of the bladder they are in apposition for a
distance of about four inches (10 cm.), flanked and overlapped by the
vesiculæ seminales. They form ampullæ about four or five inches (10 to
12 cm.) long and half an inch (1.2 to 1.5 cm.) wide, the mucous lining
of which is plicated. They then pass under the body of the prostate and
unite with the ducts of the vesiculæ seminales to form the ejaculatory
ducts. The latter have slit-like openings on either side of the
colliculus seminalis.
The =vesiculæ seminales= are not bladder-like sacs, as in the horse, but
are compact glandular organs with a lobulated surface. In the adult they
measure about four or five inches (ca. 10 to 12 cm.) in length, two
inches (5 cm.) in width in their largest part, and an inch or more (ca.
3 cm.) in thickness. The dorsal surface of each faces upward and inward
and is partially covered with peritoneum. The ventral surface faces in
the opposite direction and is non-peritoneal. Each may be regarded as
consisting of a very thick-walled, sacculated tube, bent on itself in a
tortuous manner. This tube, if straightened out, would be about ten
inches (25 cm.) in length. They are commonly unsymmetrical in size and
shape. Short branches are often given off from the chief tube. The
excretory duct or neck joins the outer side of the vas deferens at an
acute angle to form the ejaculatory duct.
[Illustration:
FIG. 401.—ANTERIOR EXTREMITY OF PENIS OF BULL, LEFT VIEW. (After
Böhm.)
]
[Illustration: