Chapter 19
II. Introduction
The functions of the male & female reproductive systems
are :
a) the production and nurturing of sex cells and transporting
those sex cells to sites of fertilization;
b) secrete hormones essential to the development of
secondary sexual characteristics and the regulation of
reproductive physiology.
III.
A.
2.
The primary functions of the male reproductive system are
to:
a) produce & maintain sperm;
b) transport sperm & supporting fluids to the outside (of the
male body);
c) secrete male hormones.
3. The primary organs of the male reproductive system are the 2
testes.
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B.
1. The seminiferous tubules are lined with specialized stratified
epithelial cells called spermatogenic cells (aka
spermatogonia). The spermatogonia are undifferentiated,
diploid cells (46 chromosomes) that give rise to sperm
cells.
2. The interstitial cells, (aka cells of Leydig) lie in the spaces
between the seminiferous tubules and are responsible for
producing & secreting male hormones.
3. The epithelial cells of the seminiferous tubules can give rise
to testicular cancer. This type of cancer is relatively rare
and occurs most often in young men. Usually the first sign
is a painless, testis enlargement or a scrotal mass that is
attached to a testes.
C. & D.
1. Spermatogenesis occurs throughout the reproductive life of a
male (from puberty to death).
 in the male embryo there are undifferentiated, diploid (46
chromosomes) cells called spermatogonia, or
spermatogenic cells
 during embryonic development hormones stimulate the
spermatogonia to undergo mitosis; some of the
spermatogonia enlarge to become primary spermatocytes
 at puberty, the primary spermatocytes undergo meiosis
(meiosis I and meiosis II)
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 as a result of meiosis I each primary spermatocyte (46
chromosomes) results in 2 secondary spermatocytes (23
chromosomes)
 during meiosis II each secondary spermatocyte results in 2
spermatids (23 chromosomes, haploid) which will mature
into sperm cells. Four sperm cells are the result of meiosis /
spermatogenesis
2. Once formed, the sperm cells collect in the lumen of the
seminiferous tubules and pass into the epididymis where they
accumulate and are stored.
3. A mature sperm looks like a tadpole (see ppt. slides 7-9)
D.
E.
1.
The accessory organs of the male reproductive systems are
the epididymis, vas deferens, ejaculatory ducts, uretha,
seminal vesicles, prostate glands, and bulbourethral gland.
2.
a) The epididymis is a tightly coiled tube adjacent to the
testes and leading to the vas deferens.
b) The epididymis’ function is to move non-motile,
immature sperm from the testes to the vas deferens by the
action of peristalsis. The sperm cells mature as they move
through the epididymis and by the time they reach the vas
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deferens sperm have acquired the potential to move
independently (they can swim!).
3.
The vas deferens is a muscular tube about 45cm in length
that leads from the epididymis into the pelvic cavity behind
the urinary bladder. Just outside of the prostate gland it
unites with the duct of a seminal vesicle to form an
ejaculatory duct which passes through the prostate gland &
empties into the urethra.
4.
a) The seminal vesicles are attached to the vas deferens
near the base if the urinary bladder.
b) The seminal vesicles secrete a slightly alkaline fluid that
contains fructose and prostaglandins. The alkalinity is to
regulate the pH of fluid as sperm exit the male tract;
fructose to provide energy for sperm; prostaglandins
stimulate muscular contractions within the female
reproductive organs aiding the movement of sperm toward
the egg cell.
5.
a) The prostate gland surrounds the proximal portion of the
urethra just inferior to the urinary bladder.
b) It secretes thin, milky alkaline fluid that enhances the
motility of sperm cells & neutralizes the acidity of the byproducts of spermatogenesis and the acidity of the female
reproductive tract.
6.
a) The bulbourethral glands are inferior to the prostate
gland and secrete a mucus-like fluid in response to sexual
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stimulation, lubricating the tip of the penis in preparation
for sexual intercourse.
b) The stimulation for release of the secretions of the
bulbourethral glands is sexual excitation.
7.
Seminal fluid (semen) is released in volumes between 2 to
5 mL per ejaculation and consists of sperm cells (~120
million per mL), and secretions from seminal vesicles,
prostate gland, and bulbourethral gland. The pH is ~7.5
(slightly alkaline) and includes prostaglandins and
nutrients.
NOTE: Sperm cannot naturally fertilize an egg cell but
must undergo capacitation within the female
reproductive tract before being capable of fertilizing an
egg. This capacitation reflects a weakening of the sperm
cells’ acrosomal membranes.
F.
1.
The scrotum is a pouch of skin and subcutaneous tissue that
hangs from the lower abdominal wall behind the penis.
Each chamber contains a testis. The smooth muscle of the
scrotum contracts in cold conditions (bringing testes closer
to the pelvic cavity) and relaxes in warm conditions
(allowing the scrotum to hang loosely). This action keeps
the temperature of the testes relatively constant. Optimum
temperature for sperm production is 3°C (5°F) below body
temperature.
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2.
The penis is a cylindrical organ consisting of a body, or
shaft, and a cone-shaped glans penis. The shaft contains 3
columns of erectile tissue.
3.
Parasympathetic impulses trigger the release of nitric oxide
(NO) which dilates the arteries, increasing blood flow into
the erectile tissues of the penis. This, in turn, compresses
the veins reducing blood flow away from the penis – the
result is an erection.
Emission is the movement of seminal fluid into the urethra.
Ejaculation is the forcing of semen to the outside of the
body.
4.
Male infertility is the inability of sperm cells to fertilize an
egg cell. There are multiple causes including failure of the
testes to descent into the scrotum during fetal development,
diseases such as mumps, and failure to produce sperm of
adequate number and of normal quality.
IV. Hormonal Control Of male Reproductive System
A.
1. The hypothalamus begins to secrete gonadotropin-releasing
hormone. This stimulates the secretion of gonadotropins,
luteinizing hormone (LH) and follicle stimulating hormone
(FSH), by the anterior pituitary gland.
2. Luteinizing hormone, also known as interstitial cell
stimulating hormone (ICSH) promotes the development of
testicular interstitial cells. The testicular interstitial cells
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then secrete male sex hormones (androgens), the most
abundant of which is testosterone
FSH stimulates the supporting cells of the seminiferous
tubules to respond to testosterone. Both testosterone and
FSH are needed to stimulate spermatogenic cells to
undergo spermatogenesis and produce sperm cells.
B.
1.
2.
3.
Testosterone is produced in the interstitial cells of the
testes.
During puberty, testosterone stimulates enlargement of the
testes and the accessory organs of the male reproductive
system. Also, it stimulates development of male secondary
sexual characteristics.
Male secondary sexual characteristics include increased
growth of body hair, enlargement of the larynx which
deepens the voice, thickening of the skin, increased
muscular growth resulting in broadening of the shoulders
and narrowing of the waist, and the thickening and
strengthening of the bones.
C.
By a negative feedback system controlled by the
hypothalamus:
 as blood levels of testosterone rise, the hypothalamus
secretes less gonadotropin. The level of LH (ICSH)
production by the pituitary falls and the amount of
testosterone release by the cells of the testes
decreases;
 as testosterone levels fall, the hypothalamus
stimulates the pituitary to secrete LH (ICSH).
Female Reproductive System
7
Functions:
 to produce & maintain oocytes (egg cells)
 to transport oocytes to the site of fertilization
 to provide a favorable environment for a developing
offspring & to move the offspring into the outside
 to produce female hormones
Primary female sex organs are the ovaries.
B.
The ovaries are solid, ovoid structures found in the lateral
walls of the pelvic cavity consisting of 2 layers.
 Inner layer – medulla is composed of loose connective
tissue with many blood vessels, lymphatic vessels, and
nerve fibers.
 Outer cortex – has more compact tissue that contains
many ovarian follicles; the outer surface of the ovary
is covered with cuboidal epithelial tissue.
C.
1.
Prenatal:
Ovarian cortex forms several million primordial follicles.
Each follicle contains a single large cell (the primary
oocyte - diploid) surrounded by follicle cells
At Puberty:
Some of the primary oocytes are stimulated to continue
meiosis & form a secondary oocyte (haploid) and a first
polar body (this is an unequal division – the polar body is
small)
Upon Fertilization:
When the large secondary oocyte is fertilized it divides
again to form a large fertilized egg (zygote) and a second
polar body.
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The reason for the polar bodies is to concentrate the
cytoplasm in the oocyte. The polar bodies have no
reproductive functions and will degenerate.
D.
1.
2.
E.
1.
2.
F.
1.
2.
3.
The release of FSH (follicle stimulating hormone) by the
anterior pituitary gland stimulates the maturation of a
primary follicle.
The primary oocyte enlarges and surrounding follicular
cells proliferate by mitosis. The surrounding cells organize
into layers and a cavity forms. When the follicle matures a
secondary oocyte is released.
A surge of luteinizing hormone (LH) is released from the
anterior pituitary gland.
The oocyte & its surrounding layers of follicular cells is
propelled toward the opening of the uterine tube (aka
fallopian tube).
Drawing to label
The uterine tube is lined with simple columnar epithelial
cells, some of which are ciliated. The epithelial cells
secrete mucus and the cilia beat toward the uterus. These
actions help draw the secondary oocyte into the uterine
tube. Once in the tube, ciliary action and peristaltic
contractions move the egg along the tube to the uterus.
b) The layers of the uterine wall are the inner glandular
endometrium, the middle (smooth) muscular layer or
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myometrium, and the outer serosal perimetrium (serous
membrane. The endometrium and the myometrium
undergo regular changes during the monthly reproductive
cycles and during pregnancy.
4.
a) The functions of the vagina are:
 to convey uterine secretions to the outside
 to receive the penis during sexual intercourse
 to provide an open channel for offspring during birth
b) The vagina is a 3- layered fibromuscular tube extending
upward and back into the pelvic cavity anterior to the
rectum and posterior to the bladder. The hymen is a
thick layer of connective tissue and stratified squamous
epithelium that partially obscures the vaginal orifice.
The wall of the vagina consists of an inner mucosal
layer, a middle muscular layer, and an outer fibrous layer
that attaches the uterus to the surrounding organs.
G.
1.
2.
3.
4.
The labia majora correspond to the scrotum in the male;
they both surround and protect the other external female
reproductive organs.
The labia minora are flattened longitudinal folds between
the labia major that form a hood around the clitoris.
The clitoris corresponds to, and has structures similar to,
the penis.
a) The space enclosed by the labia minora is the vestibule.
The vestibule contains the vagina; the vagina opens into the
posterior portion. The urethra opens in the midline of the
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5.
vestibule and is anterior to the vagina. The vestibule also
contains the vestibular glands that correspond to the
bulbourethral glands in the male.
b) The function of the vestibular glands is to secrete a
mucus-like lubricating fluid.
Erectile tissues in the clitoris and around the vaginal orifice
respond to sexual stimulation. Parasympathetic nerve
impulses from the sacral portion of the spinal cord release
nitric oxide, causing vasodilatation & swelling of erectile
tissue and expansion & elongation of the vagina.
VI.
A.
1.
The hypothalamus begins to secrete increasing amounts of
gonadotropin-releasing hormones (GnRH), which in turn
stimulates the pituitary to release LH (luteinizing hormone)
& FSH (follicle-stimulating hormone).
2. Female sex hormones are secreted by the ovaries, the
adrenal cortices (endocrine gland above the kidney) and
during pregnancy the placenta secretes hormones.
3. Estrogen is responsible for the development & maintenance
of female secondary sex characteristics which include
breast development and the ductile system of the mammary
glands, increased deposition of fat tissue in the
subcutaneous layer generally and in the breasts, thighs, and
buttocks, and increased vascularization of the skin.
4. Progesterone promotes changes in the uterus during the
female cycle, affects mammary glands, and helps regulate
the secretion of gonadotropins from the anterior pituitary.
5. Androgens are responsible for increased hair growth in the
axillary (underarm) and pubic areas during adolescence.
Low concentrations of androgens account for the female
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skeletal development, which includes narrow shoulders and
broad hips.
B.
1.
When the ovaries & other reproductive organs are mature
enough to respond to threshold levels of FSH and LH, these
hormones are released from the pituitary gland and the
female’s first menstrual cycle called menarche occurs.
 FSH stimulates the maturation of follicular cells.
 LH stimulates certain ovarian cells to produce
precursor molecules of testosterone that is then
converted to estrogen.
2.
 During the first week of the menstrual cycle, estrogen
levels increase causing a thickening of the glandular
endometrium of the uterus. This is called the proliferative
phase. As the proliferative phase proceeds, the estrogen is
also causing maturation of a primary follicle.
 By the fourteenth day of the cycle the follicle appears on
the surface of the ovary and follicular fluid accumulates
rapidly. Maturation of the follicle was accompanied by
inhibition of LH secretion by the pituitary. When the
follicle is mature, this inhibition ceases producing a surge
in LH secretion.
 The LH surge produces rupture of the mature follicle and
release of the oocyte in ovulation. Once the follicle is
ruptured, blood fills the empty follicle. The blood clots.

LH causes the follicular cells to enlarge and form a
temporary glandular structure called the corpus luteum.
The cells of the corpus luteum secrete large amount of
progesterone and estrogen during the last stage of the
menstrual cycle.
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 Progesterone stimulates the endometrium of the uterus to
become more vascular and glandular as well as stimulating
uterine glands to secrete glycogen and lipids. This creates
an environment that will support development of an
embryo.
 Additional follicles cannot mature and rupture because the
levels of estrogen and progesterone produced by the corpus
luteum prevent release of FSH and LH.
 If a sperm fails to fertilize the oocyte, the corpus luteum
begins to degenerate about the twenty-fourth day of the
cycle. This results in the formation of a corpus albicans.
 Levels of estrogen and progesterone decline as the corpus
luteum degenerates, blood vessels in the endometrium
constrict decreasing the supply of oxygen and nutrients to
the endometrium.
 The lining begins to degenerate and is shed as menstrual
flow on about the twenty-eighth day of the menstrual cycle.
This is the end of the cycle and the process begins again
with the release of increasing levels of FSH and LH.
3.
C.
1.
Women athletes may have decreased menstrual flow or
complete cessation of menses due to low levels of adipose
tissue. This leads to a decrease in estrogen.
Menopause (aka female climacteric) is the cessation of the
menstrual cycle and occurs in the fourth to fifth decade of
life.
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2.
Menopause is due to aging of the ovaries - few primary
follicles remain that are capable of responding to
stimulation by FSH and LH. This leads to decreased levels
of estrogen and progesterone resulting in changes in the
secondary sex characteristics.
VII
A. The function of the mammary glands is to secrete milk
following delivery of a neonate.
There is increasing acceptance of the concept that breastfeeding is the optimal way to provide nutrition to an infant.
B.
C.
D.
The mammary glands are located in the breasts. (The
breasts lie over the pectoral muscles of the anterior chest
from the second to the sixth ribs).
A mammary gland consists of fifteen to twenty lobes. Each
lobe contains alveolar glands and an alveolar duct that
leads to a lactiferous duct that brings mammary gland
secretions to the surface of the breast. The mammary
glands produce milk in response to hormonal stimulation.
The purpose of monthly breast self examination is to detect
changes in the texture and appearance of the breast that
may indicate cancer of the breast.
VIII. Birth Control
Coitus interruptus is withdrawal of the penis from the
vagina prior to ejaculation of semen. It is an ineffective
method of contraception.
Rhythm method depends on avoidance of sexual
intercourse a few days before and after anticipated
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ovulation. It is relatively ineffective in preventing
pregnancy.
Mechanical barriers prevent sperm from entering the
female reproductive tract during intercourse. Mechanical
barriers include male and female condoms, diaphragms and
cervical caps. Used correctly, mechanical methods are
effective contraceptives. Male and female condoms are the
only contraceptive methods that prevent transmission of
sexually transmitted diseases.
Chemical barriers are spermicidal jellies, creams, and
foams. They are most effective when used with a condom
or a diaphragm.
Combined hormone contraceptives and birth control pills
contain synthetic estrogen and progesterone like chemicals.
They work by preventing ovulation and by interfering with
the proliferation of the endometrium. They are effective
contraceptives if taken as prescribed. They can have
serious side effects such as blood clots, liver disorders,
most frequently in women over 35 years of age. They are
not prescribed to women over 35 who continue to smoke.
One contraceptive (Lunelle) can be injected monthly.
A plastic ring impregnated with hormones can be inserted
into the vagina and provides contraception for 3 months.
A transdermal patch is another delivery method for
hormone contraceptives.
15
Injectable contraception such as Depo-Provera is a
progesterone contraceptive that lasts for three months. It
prevents the maturation and release of a secondary oocyte.
Intrauterine devices are small, solid objects placed in the
uterine cavity through the cervix. They interfere with
implantation of a blastocyst in the endometrium. They are
thought to be the most effective means of contraception and
may stay in place for several years.
Surgical methods of contraception are not reversible
except in very unusual cases. They may sterilize either the
male or the female by a vasectomy or a tubal ligation.
IX STDs
A. Many sexually transmitted diseases do not produce
symptoms early in the infection and so are symptomless.
Common symptoms include fever, weakness, painful
urination and intercourse, mucous discharge from the penis
or vagina, warts or ulcers on the genitalia or mouth or anus.
Acquired Immune Deficiency Syndrome destroys the
immune system and may present with repeated infections
of various parts of the body.
B. Complications of STD’s include sterility as a result of
pelvic inflammatory disease, decreased immunity, nervous
system damage and death.
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