because the duct system of women is incomplete—there is no physical
connection between the ovary and the uterine tubes, which are open to
the pelvic cavity. In men, the duct system is continuous from the testes to
the body exterior.
Te waving action of the ﬁmbriae and currents cre-
ated by the beating cilia help to direct the ovulated oocytes into the uterine
Te usual site of fertilization is the uterine tube. Te uterus serves
as the incubator for fetal development.
Te greater vestibular glands
are the female homologue of the male bulbo-urethral glands.
penis and clitoris are hooded by a skin fold and are largely erectile tissue.
However, the clitoris lacks a corpus spongiosum containing a urethra, so
the urinary and reproductive systems are completely separate in females.
Developmentally, the mammary glands are modiﬁed sweat glands.
Breast cancer usually arises from the epithelial cells of the small ducts.
Te products of meiosis in females are 3 polar bodies (tiny haploid
cells with essentially no cytoplasm) and 1 haploid ovum (functional gam-
ete). Meiosis in males yields 4 functional gametes, the haploid sperm.
Identical twins develop from separation of a very young embryo (the
result of fertilization by a single sperm) into two parts. Fraternal twins
develop when diﬀerent oocytes are fertilized by diﬀerent sperm.
luteal phase, the ovulated follicle develops into a corpus luteum, which
then secretes progesterone (and some estrogen).
Leptin is important
in advising the brain of the girl’s readiness (relative to energy stores) for
FSH prompts follicle growth and LH prompts ovulation.
Estrogen exerts positive feedback on the anterior pituitary that leads
to a burstlike release of LH.
Estrogen is responsible for the secondary
sex characteristics of females.
Estrogen promotes epiphyseal closure in
both males and females.
Te human papillomavirus (HPV) is most as-
sociated with cervical cancer.
Chlamydia is the most common bacterial
sexually transmitted infection in the U.S.
No. If the sex chromosomes
are XY, a male baby will develop.
Te sexually indiﬀerent stage of
development is the early period when the presumptive reproductive struc-
tures can produce either male or female organs.
guides the descent of the testis into the scrotum.
Early signs of pu-
berty’s onset in boys are enlargement of the testes and scrotum.
pause has happened when menstruation has not occurred for a year.
Review Questions 1.
a and b;
a, c, e,
(1)c, f; (2)e, h; (3)g; (4)a; (5)b, e, and g; (6)f;
Case Study 1.
Carcinoma is the term for cancer originating from epithe-
lial tissue. Te primary source of Mr. Heyden’s cancer is likely to be the
Elevation of PSA levels suggests carcinoma of the prostate.
(In addition, Mr. Heyden’s age places him in a group that is at relatively
higher risk for this type of cancer.)
Digital examination of Mr. Hey-
den’s prostate should detect the presence of carcinoma in this tissue. In
addition, transrectal ultrasound imaging may be used in screening, and
biopsies of prostate tissue follow positive results of tests.
carcinoma has advanced to the point of metastasis. He will probably un-
dergo a treatment that reduces the levels of androgens in his body, as an-
drogens promote growth of the prostate-derived tissue. Tese treatments
could include castration or administration of drugs that block the produc-
tion and/or eﬀects of androgens.
Check Your Understanding 1.
Before they can penetrate an oocyte,
sperm must be capacitated, and an oocyte’s zona pellucida must be
eroded by the acrosomal enzymes of many sperm.
Te cortical reac-
tion, or slow block to polyspermy, involves the release of enzymes from
cortical granules to the oocyte exterior, which accomplishes destruction
of the oocyte’s sperm receptors and also the detachment of any sperm
still bound to receptors. Tese events ensure monospermy.
cyst is only slightly larger than the zygote because, although cell division
has been going on (cleavage divisions), there is essentially no time for
constrictor and will increase blood pressure, and it promotes water reten-
tion by the kidney, increasing blood volume.
(a) Mr. Heyden’s urine
production may be decreased for several reasons. Te severe drop in his
blood pressure would reduce renal blood ﬂow, thus reducing glomerular
blood pressure and decreasing his glomerular ﬁltration rate. Te eleva-
tion in his ADH levels can reduce urine output due to increased water
reabsorption by the kidney. He may also have damage to the kidney due
to his crush injury in the le± lumbar region. (b) Te presence of casts
and a brownish-red color in his urine are probably due to damaged cells
and blood. If he has suﬀered kidney damage due to being crushed, he
may have nephron damage that would include disruption of the ﬁltration
membrane, allowing red blood cells to pass into the ﬁltrate and therefore
the urine. He may also have damaged renal tubules and peritubular capil-
laries, allowing entry of blood and damaged renal tubule epithelial cells
into the ﬁltrate.
Check Your Understanding 1.
Te testes produce the male gametes
(sperm) and testosterone.
Te sperm factories are the seminiferous
When the ambient temperature is cold, the associated muscles
contract, bringing the testes close to the warm body wall. When body
temperature is high, the associated muscles relax, allowing the testes to
hang away from the body wall. Te pampiniform venous plexus absorbs
heat from the arterial blood before it enters the testes.
Te erectile tissue
of the penis allows the penis to become stiﬀ so that it may more eﬃciently
enter the female vagina to deliver sperm.
Te organs of the male duct
system in order from the epididymis to the body exterior are the ductus
deferens, ejaculatory duct, prostatic urethra, intermediate part of the ure-
thra, and spongy urethra.
Tese stereocilia pass nutrients to the sperm
and absorb excess testicular ﬂuid.
Te ductus deferens runs from the
scrotum into the abdominal cavity.
Adolph probably has a hypertro-
phied prostate, a condition which can be felt through the anterior wall of
Te seminal glands produce the bulk of seminal ﬂuid.
Semen is sperm plus the secretions of the male accessory glands.
tion is the stiﬀening of the penis that occurs when blood in the cavernous
tissue is prevented from leaving the penis. It is caused by the parasympa-
thetic division of the autonomic nervous system.
Resolution is a period
of muscular and psychological relaxation that follows orgasm. It results as
the sympathetic nervous system causes constriction of the internal puden-
dal arteries, reducing blood ﬂow to the penis, and activates small muscles
that force blood out of the penis.
Meiosis reduces the chromosomal
and introduces variability.
Te sperm head is the
compacted DNA-containing nucleus. Te acrosome that caps the head
is a lysosome-like sac of enzymes. Te midpiece contains the energy-
producing mitochondria. Te tail, a ﬂagellum fashioned by a centriole, is
the propulsive structure.
Sustentocytes provide nutrients and essential
development signals to the developing sperm and form the blood testis
barrier that prevents sperm antigens from escaping into the blood. Intersti-
tial endocrine cells secrete testosterone.
Te HPG axis is the hormonal
interrelationship between the hypothalamus, anterior pituitary, and gonads
that regulates the production of gametes and sex hormones (e.g., sperm
production and testosterone in the male).
indirectly stimulates spermatogenesis by prompting the sustentocytes to
secrete androgen-binding protein. Androgen-binding protein keeps the
concentration of testosterone high in the vicinity of the spermatogenic
cells, which directly stimulates spermatogenesis.
Secondary sex char-
acteristics of males include appearance of pubic, axillary, and facial hair,
deepening of the voice, increased oiliness of the skin, and increased size
(length and mass) of the bones and skeletal muscles.
Te female’s inter-
nal genitalia include the ovaries and duct system (uterine tubes, uterus, and
Te ovaries produce the female gametes and secrete female sex
hormones (estrogens and progesterone).
Te antrum is the ﬂuid-ﬁlled
cavity of a mature follicle.
Women are more at risk for PID than men