855
CHAPTER TWENTY-TWO
Reproductive System
the vestibular glands. These structures that surround the open-
ings of the urethra and vagina compose the
vulva
(f g. 22.30)
.
Labia Majora
The
labia majora
(sing.,
labium majus
) enclose and protect
the other external reproductive organs. They correspond to
the scrotum of the male and are composed of rounded folds
of adipose tissue and a thin layer of smooth muscle, cov-
ered by skin. On the outside, this skin includes hairs, sweat
glands, and sebaceous glands, whereas on the inside, it is
thinner and hairless.
The labia majora lie close together and are separated
longitudinally by a cleft (pudendal cleft), which includes the
urethral and vaginal openings. At their anterior ends, the
labia merge to form a medial, rounded elevation of adipose
tissue called the
mons pubis,
which overlies the symphysis
pubis. At their posterior ends, the labia taper and merge into
the perineum near the anus.
Labia Minora
The labia minora (sing.,
labium minus
) are fl attened longitu-
dinal folds between the labia majora. They are composed of
connective tissue richly supplied with blood vessels, giving a
pinkish appearance. StratiF
ed squamous epithelium covers
this tissue. Posteriorly, the labia minora merge with the labia
majora, whereas anteriorly, they converge to form a hood-
like covering around the clitoris.
Clitoris
The
clitoris
(kli
to-ris) is a small projection at the anterior
end of the vulva between the labia minora. It is usually
about 2 centimeters long and 0.5 centimeter in diameter,
The vaginal wall has three layers. The inner
mucosal
layer
is stratiF
ed squamous epithelium and is drawn into
many longitudinal and transverse ridges (vaginal rugae).
This layer lacks mucous glands; the mucus in the lumen of
the vagina comes from the glands of the cervix and the ves-
tibular glands at the mouth of the vagina.
The middle
muscular layer
of the vagina mainly consists
of smooth muscle F
bers in longitudinal and circular patterns.
At the lower end of the vagina is a thin band of striated mus-
cle. This band helps close the vaginal opening; however, a
voluntary muscle (bulbospongiosus) is primarily responsible
for closing this oriF
ce.
The outer
f
brous layer
consists of dense connective tis-
sue interlaced with elastic F
bers. It attaches the vagina to
surrounding organs.
PRACTICE
37
How does a secondary oocyte move into the infundibulum
following ovulation?
38
How is a secondary oocyte moved along a uterine tube?
39
Describe the structure of the uterus.
40
What is the function of the uterus?
41
Describe the structure of the vagina.
Female External Reproductive Organs
The
external accessory organs
of the female reproductive sys-
tem include the labia majora, the labia minora, the clitoris, and
Lumen
Endometrium
Myometrium
Perimetrium
FIGURE 22.29
Light micrograph of the uterine wall (10×).
FIGURE 22.30
Female external reproductive organs and associated
structures.
Clitoris
Urethral
orifice
Vaginal
orifice
Mons pubis
Labium
majus
Labium
minus
Vestibule
Perineum
Anus
Opening of
vestibular gland
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