The Dissection of Vertebrates A Laboratory Manual

first glance, however, it appears to form a connection
between the uterine horn and ovary. Thus, carefully
follow the uterine horn into the uterine tube.
The union of the uterine horns posteriorly form the
body of the uterus, a wider canal that then leads into
the vagina. As there is no external division of these
structures, their separation will be seen when they are
opened. Note that the ureters pass dorsal to the uterine
horns.
The reproductive tract is supported by various mesenteries.
The main supporting structure is the broad
ligament, of which several portions are recognized. Lift
the reproductive structures to clearly observe the following
mesenteries. The portion of the broad ligament
supporting the ovary is the mesovarium. The mesosalpinx
attaches to the uterine tube, and the mesometrium
attaches to the uterus, including the uterine
horn. Lift the uterine horn near its center and tug it
medially, as shown in Figure 7.71. The round ligament
is the fibrous band in the mesometrium that extends
diagonally from the uterine horn posterolaterally
toward the body wall. Also, note the suspensory ovarian
ligament, which supports the ovary anteriorly, as it
extends to the dorsal body wall just lateral to the
kidney.
Open the pelvic canal by cutting through the pubic symphysis
following the instructions given for the male on
page 216. Pick away connective tissue to reveal and
separate the structures passing through the canal (see
Figure 7.71). The urethra and vagina unite toward the
posterior end of the pelvic canal to form a common
passageway, the urogenital sinus, which opens to the
outside through the urogenital aperture. Dissect dorsal
to the vagina and urogenital sinus to separate them from
the rectum. On each side, dissect the tissue lateral to the
rectum, very near the anus, to reveal the anal glands.
Then completely separate the urogenital sinus from the
rectum so that it can be turned over. Make a slit along
one side of the body of the uterus, vagina, and urogenital
sinus, and spread the flaps apart (Figure 7.72). Find
the urethral orifice, the entrance of the urethra. The
vagina extends anteriorly from this point to the cervix
of the uterus, which is the distally tapered, sphincterlike
portion of the uterus. Directly posterior to the
urethral orifice, and just before the urogenital aperture,
lies the small clitoris, which may be difficult to see. It is
the female homologue of the penis and generally considerably
smaller, but in hyenas it exceeds the penis in
size.
The mammary glands are important reproductive structures
in mammals. They were observed beneath the skin
of the thorax and abdomen during skinning of the cat
(see page 157).
Dissection
area
Cervix (cut
and reflected)
External
urethral orifice
Openings of
vestibular glands
Openings
of glands
Fossa of
clitoris
Clitoris
Labia
Urethra
KEY TERMS: FEMALE REPRODUCTIVE SYSTEM
anal glands
infundibulum
body of the uterus
mammary glands
broad ligament
mesometrium
cervix of the uterus mesosalpinx
clitoris
mesovarium
fimbriae
ostium tubae
Vagina
Vestibule
FIGURE 7.72 Distal portion of female urogenital tract of the
cat in ventral view. The tract has been cut along its lateral
margin and opened to the right to reveal the internal anatomy.
SECTION VI—UROGENITAL SYSTEM 217