847
CHAPTER TWENTY-TWO
Reproductive System
Ovary Structure
The tissues of an ovary can be subdivided into two rather
indistinct regions, an inner
medulla
and an outer
cortex.
The
ovarian medulla is mostly composed of loose connective tis-
sue and contains many blood vessels, lymphatic vessels, and
nerve F
bers. The ovarian cortex consists of more compact
tissue and has a granular appearance due to tiny masses of
cells called
ovarian follicles.
A layer of cuboidal epithelial cells (germinal epithelium)
covers the free surface of the ovary. Just beneath this epithe-
lium is a layer of dense connective tissue called the
tunica
albuginea
(too
nı˘-kah al
bu-jin
e-ah).
PRACTICE
29
What are the primary sex organs of the female?
30
Describe the descent of the ovary.
31
Describe the structure of an ovary.
Primordial Follicles
During prenatal (before birth) development of a female,
oogonia divide by mitosis to produce more oogonia. The
oogonia develop into
primary oocytes.
Each primary oocyte
is closely surrounded by a layer of fl
attened epithelial cells
called
follicular cells,
forming a
primordial follicle.
Ovaries
The two
ovaries
are solid, ovoid structures measuring about
3.5 centimeters in length, 2 centimeters in width, and 1 cen-
timeter in thickness. The ovaries lie in shallow depressions
(ovarian fossae) on each side in the lateral wall of the pelvic
cavity
(f g. 22.20)
.
Ovary Attachments
Several ligaments help hold each ovary in position. The larg-
est of these, formed by a fold of peritoneum, is called the
broad ligament.
It is also attached to the uterine tubes and
the uterus.
A small fold of peritoneum, called the
suspensory liga-
ment,
holds the ovary at its upper end. This ligament also
contains the ovarian blood vessels and nerves. At its lower
end, the ovary is attached to the uterus by a rounded, cord-
like thickening of the broad ligament called the
ovarian liga-
ment
(F g. 22.20).
Ovary Descent
Like the testes in a male fetus, the ovaries in a female fetus
originate from masses of tissue posterior to the parietal peri-
toneum, near the developing kidneys. During development,
these structures descend to locations just inferior to the pel-
vic brim, where they remain attached to the lateral pelvic
wall.
FIGURE 22.18
The hypothalamus controls maturation of sperm cells and development of male secondary sex characteristics. Negative feedback
among the hypothalamus, the anterior lobe of the pituitary gland, and the testes controls the concentration of testosterone in the male body.
Bloodstream
Hypothalamus
Pituitary
gland
GnRH
FSH
LH
Androgens prevent
oversecretion of GnRH
Androgens prevent over-
secretion of LH
Inhibin prevents
oversecretion of FSH
Androgens stimulate
the development
of male secondary
sex characteristics
and maturation of
sperm cells
Inhibin
Testosterone and
other androgens
Testes
FSH stimulates meiosis
in primary spermatocytes
to form immature sperm
cells; FSH stimulates
secretion of inhibin by
supporting cells
LH stimulates
interstitial cells to
secrete androgens
(primarily testosterone)
+
+
+
Release into
bloodstream
Stimulation
Inhibition
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