871
CHAPTER TWENTY-TWO
Reproductive System
b. Uterus
(1) The uterus receives the embryo and sustains it
during development.
(2) The uterine wall includes the endometrium,
myometrium, and perimetrium.
c. Vagina
(1) The vagina connects the uterus to the
vestibule.
(2) It receives the erect penis, conveys uterine
secretions to the outside, and provides an open
channel for the fetus during birth.
(3) A thin membrane, the hymen, partially closes
the vaginal oriF
ce.
(4) The vaginal wall consists of a mucosa,
muscularis, and outer F
brous coat.
3. ±emale external reproductive organs
a. Labia majora
(1) The labia majora are rounded folds of adipose
tissue and skin that enclose and protect the
other external reproductive parts.
(2) The anterior ends form a rounded elevation
over the symphysis pubis.
b. Labia minora
(1) The labia minora are fl
attened, longitudinal
folds between the labia majora.
(2) They are well supplied with blood vessels.
c. Clitoris
(1) The clitoris is a small projection at the anterior
end of the vulva; it corresponds to the male
penis.
(2) It is composed of two columns of erectile
tissue.
(3) Its root is attached to the sides of the pubic
arch.
d. Vestibule
(1) The vestibule is the space between the labia
minora that encloses the vaginal and urethral
openings.
(2) The vestibular glands secrete mucus into the
vestibule during sexual stimulation.
e. Erection, lubrication, and orgasm
(1) During periods of sexual stimulation, the
erectile tissues of the clitoris and vestibular
bulbs become engorged with blood and
swollen.
(2) The vestibular glands secrete mucus into the
vestibule and vagina.
(3) During orgasm, the muscles of the perineum,
uterine wall, and uterine tubes contract
rhythmically.
22.5
HORMONAL CONTROL OF FEMALE
REPRODUCTIVE FUNCTIONS (PAGE 857)
Hormones from the hypothalamus, anterior pituitary
gland, and ovaries play important roles in the control of
sex cell maturation, the development and maintenance
of female secondary sex characteristics, and changes that
occur during the monthly reproductive cycle.
1. ±emale sex hormones
a. A female body remains reproductively immature
until about ten years of age, when gonadotropin
secretion increases.
b. Ovary descent
(1) The ovaries descend from posterior to the
parietal peritoneum near the developing
kidneys.
(2) They are attached to the pelvic wall just
inferior to the pelvic brim.
c. Ovary structure
(1) The ovaries are subdivided into a medulla and
a cortex.
(2) The medulla is composed of connective tissue,
blood vessels, lymphatic vessels, and nerves.
(3) The cortex contains ovarian follicles and is
covered by cuboidal epithelium.
d. Primordial follicles
(1) During prenatal development, oogonia divide
by mitosis to produce more oogonia that
develop into primary oocytes.
(2) Each primordial follicle contains a primary
oocyte and a layer of fl
attened epithelial cells.
(3) The primary oocyte begins to undergo meiosis,
but the process soon halts and does not
resume until puberty.
(4) The number of oocytes steadily declines
throughout the life of a female.
e. Oogenesis
(1) Beginning at puberty, some oocytes are
stimulated to continue meiosis.
(2) When a primary oocyte undergoes oogenesis,
it gives rise to a secondary oocyte in which the
original chromosome number is halved (from
46 to 23).
(3) A secondary oocyte may be fertilized to
produce a zygote.
f. ±ollicle maturation
(1) At puberty, ±SH initiates follicle maturation.
(2) During maturation of the follicle, the primary
oocyte enlarges, the follicular cells proliferate,
and a fl uid-F
lled cavity appears and produces
a secondary follicle.
(3) Ovarian cells surrounding the follicle form two
layers.
(4) A mature follicle contains a secondary oocyte
surrounded by a zona pellucida and corona
radiata.
(5) Usually only one follicle per reproductive cycle
reaches full development.
g. Ovulation
(1) Ovulation is the release of a secondary oocyte
from an ovary.
(2) The secondary oocyte is released when its
follicle ruptures.
(3) After ovulation, the secondary oocyte is drawn
into the opening of the uterine tube.
2. ±emale internal accessory organs
a. Uterine tubes
(1) These tubes convey egg cells toward the
uterus.
(2) The end of each uterine tube is expanded, and
its margin bears irregular extensions.
(3) Ciliated cells that line the tube and peristaltic
contractions in the wall of the tube move an
egg cell into the tube’s opening.
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