REPRODUCTIVE SYSTEM
MALE REPRODUCTIVE ORGANS
ANATOMY
OF
THE MALE REPRODUCTIVE SYSTEM
•
The scrotum is a sac of skin and
superficial fascia that hangs outside the
abdominopelvic cavity at the root of the
penis and houses the testes
– Provides an environment three
degrees below the core body
temperature
– Responds to temperature changes:
help maintain a fairly constant
intrascrotal temperature and reflects
the activity of two sets of scrotal
muscles
• When it is cold, the testes are
pulled closer to the warmth of the
body wall, and the scrotum
becomes shorter and heavily
wrinkled to reduce heat loss
• When it is warm, the scrotal skin
is flaccid and loose to increase the
surface area for cooling, and the
testes hang lower
TESTIS STRUCTURE
ANATOMY
OF
THE MALE REPRODUCTIVE SYSTEM
• The testes are the primary
reproductive organ of the
male, producing both sperm
and testosterone
• The testes are divided into
lobules with seminiferous
tubules inside, where sperm
are produced
– Each lobule converge to form
a tubule that conveys sperm to
the epididymis which hugs
the external testis surface
• Interstitial cells are found in
the connective tissue
surrounding the
seminiferous tubules and
produce testosterone
INTERNAL STRUCTURE OF
TESTIS
ANATOMY
OF
THE MALE REPRODUCTIVE SYSTEM
• Spermatic cord:
connective tissue
sheath enclosing:
–
–
–
–
–
Testicular arteries
Testicular veins
Lymph vessels
Nerves
Vas (ductus)
deferens
INTERNAL STRUCTURE OF
TESTIS
TESTIS STRUCTURE
MALE REPRODUCTIVE ORGANS
HOMEOSTATIC IMBALANCE
• Although testicular cancer is relatively
rare, it is the most common cancer in
young men (15-35)
• A history of mumps or orchitis
(inflammation of the testis) increases the
risk, but the most important risk factor for
this cancer is cryptorchidism (nondescent
of the testes)
ANATOMY
OF
THE MALE REPRODUCTIVE SYSTEM
•
The penis is the copulatory organ,
designed to deliver sperm into the female
reproductive tract:
– The penis is made of an attached root,
a free shaft or body that ends in the
glans
– The prepuce, or foreskin, covers the
penis and may be slipped back to
form a cuff around the glans
• Removed in a procedure called
circumcision
– Internally the penis contains the corpus
spongiosum (surrounds the urethra)
and the corpora cavernosum (paired
dorsally), two erectile tissues:
• Spongy network of connective
tissue and smooth muscle
riddled with vascular spaces
• During sexual excitement, the
vascular spaces fill with blood,
causing the penis to enlarge
and become rigid (erection)
– Enables the penis to serve
as a penetrating organ
STRUCTURE OF PENIS
Male Duct System
Epididymis
• Epididymis consists of a highly coiled tube that provides
a place for immature sperm to mature and to be
expelled during ejaculation
– Gain increased motility and fertilizing power
• When a male is sexually stimulated and ejaculates,
the smooth muscle in the epididymis walls
contracts, expelling sperm into the next segment of
the duct system, the ductus (vas) deferens
• Sperm can be stored in the epididymis for several
months, but if held longer, they are eventually
phagocytized by epithelial cells of the epididymis
Male Duct System
Ductus Deferens and Ejaculatory Duct
• The ductus deferens, or vas
deferens, carries sperm from
storage sites in the epididymis,
through the inguinal canal,
over the urinary bladder, and
into the ejaculatory duct
• Each ejaculatory duct enters
the prostate gland where it
empties into the urethra
– Smooth muscles in its
walls create strong
peristaltic waves that
rapidly squeeze the
sperm forward
Male Duct System
Ductus Deferens and Ejaculatory Duct
• Vasectomy:
– Minor operation in which a
small incision is made into
the scrotum and then cuts
through and ligates (ties
off/ cut) the ductus (vas)
deferens
• Sperm are still produced
for the next several years,
but they can no longer
reach the body exterior
– They deteriorate and
are phagocytized
Vasectomy
Vasectomy
Vasectomy
Vasectomy
Male Duct System
Urethra
• The urethra is the
terminal portion of the
male duct system and
carries both urine and
sperm (not at the
same time) to the
exterior environment
MALE REPRODUCTIVE ORGANS
THE MALE REPRODUCTIVE SYSTEM
Accessory Glands
•
•
The paired seminal vesicles: on the
posterior urinary bladder wall: accounts for
60%of the volume of semen
Fluid produced contains:
– An alkaline secretion:
• Neutralizes the acid environment
of the male’s urethra and the
female’s vagina, thereby
protecting the delicate sperm and
enhancing their motility
– Coagulating enzyme (vesiculase)
• Coagulates the semen after it is
ejaculated
– Liquified by enzyme
fibrinolysin
– Provides nearly all the nutrients
• Fructose, ascorbic acid
– Prostaglandins: decreases the
viscosity of mucus guarding the
entry (cervix) of the uterus and
stimulates reverse peristalsis in the
uterus, facilitating sperm movement
through the female reproductive
tract
MALE REPRODUCTIVE ORGANS
THE MALE REPRODUCTIVE SYSTEM
Accessory Glands
•
•
The single prostate gland: milky
fluid about 30% of semen
Fluid produced:
– A slightly acidic secretion
– Citrate: compound of citric acid
and a base (nutrient source)
– Several enzymes:
• Fibrinolysin: liquifies the
coagulated mass due to the
coagulating enzyme vesiculase
– Enables the sperm to swim out of
the mass and begin their journey
through the female duct system
• Hyaluronidase: breaks down
covering of ovum
• Acid phosphate: demineralization
or resorptioin of bone
• Prostate-specific antigen (PSA):
increases sperm motility
MALE REPRODUCTIVE ORGANS
THE MALE REPRODUCTIVE SYSTEM
Accessory Glands
• The paired
bulbourethral
glands,or Cowper’s
glands:
– Produce a thick, clear
mucus prior to
ejaculation that
neutralizes any
acidic urine in the
urethra and female
vagina
MALE REPRODUCTIVE ORGANS
SEMEN
• Semen is a milky white, somewhat sticky mixture of
sperm and accessory gland secretions that provide
nutrients, neutralizing agents, and transport medium
for sperm:
– Additional components:
• Hormone relaxin: enhance sperm motility
• pH: 7.2-7.6
– Helps neutralize the acid environment of the male urethra and the
female’s vagina
– Very sluggish in acidic conditions (below pH 6)
• Antibiotic: seminalplasmin
– Destroys certain bacteria
• 2-5 ml per ejaculation (50-130 million sperm per
millimeter)
MALE REPRODUCTIVE ORGANS
PHYSIOLOGY
OF
THE MALE REPRODUCTIVE SYSTEM
• Male Sexual Response:
– Erection, enlargement, and stiffening of the
penis results from the engorgement of the
erectile tissues with blood triggered during
sexual excitement
– Ejaculation is the propulsion of semen from
the male duct system triggered by the
sympathetic nervous system
Erection
•
•
•
•
Enlargement and stiffening of the penis
Results from the engorgement of the erectile
bodies with blood
Not sexually aroused:
– Arterioles supplying the erectile tissue are
constricted and the penis is flaccid
During sexual excitement:
– Parasympathetic reflex is triggered that
promotes release of nitric oxide locally
• Nitric oxide (NO) relaxes vascular
smooth muscle, causing these
arterioles to dilate
– Allows the erectile bodies to
fill with blood
– Expansion of the corpora
cavernosa of the penis
compresses their drainage
veins, retarding blood outflow
and maintaining engorgement
– Corpus spongiosum expands
but not nearly as much as the
cavernosa
» Its main job is to keep
the urethra open during
ejaculation
• Stimulates the bulbourethral
(Cowper’s) gland secretion which
causes lubrication of the glans penis
Ejaculation
•
Propulsion of semen from the male
duct system:
–
•
While erection is under
parasympathetic control, ejaculation
is under sympathetic control
When impulses provoking erection
reach a certain critical level, a spinal
reflex is initiated, and a massive
discharge of nerve impulses occurs
over the sympathetic nerves serving
the genital organs (L1 and L2) causes:
–
Climax/orgasm:
•
•
•
The reproductive ducts and
accessory glands contract, emptying
their contents into the urethra
The urinary bladder sphincter
muscle constricts, preventing
expulsion of urine or reflux of semen
into the urinary bladder
The bulbospongiosus muscles of the
penis undergo a rapid series of
contraction, propelling semen at a
speed of up to 500 cm/s (200 inches/s)
from the urethra
STRUCTURE OF PENIS
Spermatogenesis
• A series of events in the seminiferous
tubules that produce male gametes
(sperm or spermatozoa)
• Every day, a healthy adult male produces
about 400 million sperm
HUMAN LIFE CYCLE
• Diploid (Somatic
cells) chromosomal
number (2n): 46
– 23 homologous pairs
• One member of each
pair from Mom
• One member of each
from Dad
– Therefore:
• 23 chromosomes from
Mom
• 23 chromosomes from
Dad
HUMAN LIFE CYCLE
• Haploid (Monoploid)
chromosome number
(n): 23
• Produced by Meiosis
• Homologous
chromosomes
separate
– Each gametes
contains only one
member of each
homologous pair
HUMAN LIFE CYCLE
Spermatogenesis
• Meiosis consists of two consecutive nuclear
divisions and the production of four
daughter cells with half as many cells as a
normal body cell:
– Meiosis I: reduces the number of chromosomes in a
cell from 46 to 23 by separating homologous
chromosomes into different cells
– Meiosis II: resembles mitosis in every way, except
the chromatids are separated into four cells
COMPARISON OF MITOSIS AND MEIOSIS IN A MOTHER
CELL WITH A DIPLOID NUMBER (2N) OF 4
MEIOTIC CELL DIVISION
INTERPHASE
MEIOSIS I
MEIOSIS II
INTERNAL STRUCTURE OF
TESTIS
SCANNING ELECTRON MICROGRAPH OF A
CROSS-SECTIONAL VIEW OF A
SEMINIFEROUS TUBULE
Mitosis of Spermatogonia
• Outermost tubule cells,
which are in direct
contact with the epithelial
basal lamina, are stem
cells called
spermatogonia:
– Divide by mitosis
– Until puberty all their
daughter cells become
spermatogonia
SPERMATOGENESIS
Spermatogenesis
Formation of Spermatocytes
• Begins during puberty
• After (puberty), each mitotic
division of a spermatogonium
results in two distinctive
daughter cells
– Type A daughter cell:
• Remains at the basement
membrane to maintain the
germ cell line (stem cell
line)
– Type B daughter cell:
• Gets pushed toward the
lumen, where it becomes a
primary spermatocyte
destined to produce four
sperm
SPERMATOGENESIS
Meiosis: Spermatocytes to Spermatids
• Each primary
spermatocyte
generated during the
first phase undergoes:
one replication followed
by two divisions:
– Meiosis I: forming two
smaller secondary
spermatocytes
– Meiosis II: secondary
spermatocytes divide
forming four early
spermatids (n)
• Closer to the lumen of the
tubule
• Nonmotile
SPERMATOGENESIS
Spermiogenesis: Spermatids to Sperm
•
•
•
•
A streamlining process that
strips the spermatid of excess
cytoplasm and forms a tail
resulting in a sperm with a
head, a midpiece, and a tail
Now is a sperm (spermatozoon)
Head: contains the nucleus
Acrosome:
– Lysosome-like
– Produced by Golgi apparatus
– Contains hydrolytic enzymes
• Enable sperm to penetrate and
enter egg
•
•
Midpiece: mitochondria tightly
packed around the contractile
filaments
Tail: typical flagellum produced by
a centriole
TRANSFORMATION OF
SPERMATID INTO SPERM
Role of the Sustentacular Cells
Sertoli Cells
• Throughout
spermatogenesis,
descendants of the same
speramatogonium remain
closely attached to one
another by cytoplasmic
bridges:
– They are also surrounded
by and connected to
supporting cells of a
special type, called
sustentacular cells
(Sertoli cells), which
extend from the basal
lamina to the lumen of
the tubule
SPERMATOGENESIS
Role of the Sustentacular Cells
Sertoli Cells
• The sustentacular cells, bound
to each other by tight
junctions, divide the
seminiferous tubule into two
compartments
– Basal compartment extends
from the basal lamina to their
tight junctions and contains
spermatogonia and the
earliest primary spermatocytes
– Adluminal compartment lies
internal to the tight junction
and includes the meiotically
active cells and the tubule
lumen
SPERMATOGENESIS
Role of the Sustentacular Cells
Sertoli Cells
•
Tight junctions between the
sustentacular cells form a
blood-testis barrier that
prevents membrane-bound
antigens of differentiating
sperm from escaping through
the basal lamina into the
bloodstream:
– Because sperm are not formed
until puberty, they are absent
when the immune system is
being programmed to recognize
one’s own tissues early in life
– The spermatogonia, which are
recognized as “self”, are
outside the barrier and thus can
be influenced by bloodborne
chemical messengers that
prompt spermatogenesis
SPERMATOGENESIS
HOMEOSTATIC IMBALANCE
•
•
According to some studies, a gradual decline in male fertility has been
occurring in the past 50 years
Some believe the main cause is environmental toxins, PVCs (polyvinyl
chloride) used in plastics (water lines, etc), or especially compounds
with estrogenic effects:
– These compounds, which block the action of male sex hormones as they
program sexual development, are now found in our meat supply as well as
in the air
•
•
•
Common antibiotics such as tetracycline may suppress sperm
formation; and radiation, lead, certain components of pesticides,
marijuana, lack of selenium, and excessive alcohol can cause
abnormal (two-headed, multiple-tailed, etc.) sperm to be produced
Male infertility may also be caused by the lack of a specific type of
Ca2+ channel (Ca2+ is needed for normal sperm motility), anatomical
obstructions, and hormonal imbalances
A low sperm count accompanied by a high percentage of immature
sperm may hint a man has a varicocele (condition that hinders
drainage of the testicular vein, resulting in an elevated temperature in
the scrotum that interferes with normal sperm development)
Hormonal Regulation of Male
Reproductive Function
• Involves interactions
between the hypothalamus,
anterior pituitary gland, and
testes, a relationship
sometimes called the braintesticular axis:
– 1.The hypothalamus
releases gonadotropinreleasing hormone (GnRH),
which controls the release of
the anterior pituitary
gonadotropins, folliclestimulating hormone (FSH)
and luteinizing hormone
(LH)
• Both FSH and LH were
named for their effects on
the female gonad
Hormonal Regulation of Male
Reproductive Function
• 2. Binding of GnRH
to pituitary cells
(gonadotrophs)
prompts them to
secrete FSH and LH
into the blood
Hormonal Regulation of Male
Reproductive Function
• 3. FSH stimulates
spermatogenesis indirectly:
– FSH stimulates the
sustentacular cells to
release androgen-binding
protein (ABP)
– ABP prompts the
spermatogenic cells to
bind and concentrate
testosterone, which in
turn stimulates
spermatogenesis
– Thus, FSH makes the
cells receptive to
testosterone’s
stimulatory effects
Hormonal Regulation of Male
Reproductive Function
• 4. LH, also called
interstitial cellstimulating hormone
(ICSH) in males:
– Binds to the interstitial
cells, prodding them to
secrete testosterone (and
a small amount of
estrogen)
• Locally, testosterone
serves as the final
trigger for
spermatogenesis
• Testosterone entering
the bloodstream exerts a
number of effects at
other body sites
Hormonal Regulation of Male
Reproductive Function
•
5. Testosterone inhibits hypothalamus
release of GnRH and acts directly on the
anterior pituitary gland to inhibit
gonadotropin release (negative
feedback):
– Inhibin, a protein hormone produced
by the sustentacular cells serves as a
barometer of the normalcy of
spermatogenesis (negative
feedback):
• When the sperm count is high,
inhibin release increases and it
inhibits anterior pituitary
release of FSH and
hypothalamus release of GnRH
• When sperm count falls below 20
million/ml, inhibin secretion
declines steeply and increases
the pituitary FSH release and
the hypothalamus GnRH
release
BRAIN-TESTICULAR AXIS
HORMONAL REGULATION OF TESTICULAR
FUNCTION
Mechanism and Effects of
Testosterone Activity
• Testosterone is synthesized from cholesterol and exerts its
effect by activating specific genes to transcribe messenger
RNA molecules, which results in enhanced synthesis of certain
proteins in the target cells
– Testosterone targets accessory organs (ducts, glands, and
penis) causing them to grow and assume adult size and
function
• In some target cells, testosterone must be transformed
into another steroid to exert its effect:
– Prostate gland: converted to dihydrotestosterone (DHT)
– Certain neurons of the brain to estrogen
– Testosterone induces male secondary sex characteristics:
pubic, axillary, and facial hair, deepening of the voice
(enlargement of larynx), thickening of the skin and an
increase in oil production, and an increase in bone and
skeletal muscle size and mass
– Small amounts are produced in the adrenal cortex glands
BRAIN-TESTICULAR AXIS
HORMONAL REGULATION OF TESTICULAR
FUNCTION
ANATOMY
OF
THE FEMALE RERODUCTIVE SYSTEM
• The ovaries, the female
gonads, are the primary
reproductive organs of the
female
• The ovaries produce the
female gametes (ova or egg)
and the sex hormones
(estrogen and progesterone)
• The accessory ducts
(uterine tubes, uterus, and
vagina) transport or
otherwise serve the needs of
the reproductive cells and a
developing fetus
MIDSAGITTAL SECTION OF FEMALE PELVIS
SHOWING ORGANS OF FEMALE
REPRODUCTIVE SYSTEM
OVARIES
• The paired ovaries are found
on either side of the uterus
and are held in place by
several ligaments:
– Broad ligament: a peritoneal
fold that “tents” over the uterus
and supports the uterine
tubes, uterus, and vagina
• Encloses the following
individual ligaments:
– Ovarian ligament anchors
the ovary medially to the
uterus
– Suspensory ligament
anchors the ovary laterally
to the pelvic wall
– Mesovarium suspends the
ovary in between
POSTERIOR VIEW OF FEMALE
REPRODUCTIVE ORGANS
OVARIES
• The arteries are served
by the ovarian arteries,
branches of the
abdominal aorta and by
the ovarian branch of the
uterine arteries
• The ovarian blood
vessels reach the ovaries
by traveling through the
suspensory ligaments
and mesovaria
OVARIES
• Like a testis, an ovary is
surrounded externally by a
fibrous tuncia albuginea, which
is in turn covered externally by
a layer of cuboidal epithelial
cells called the germinal
epithelium, which is
continuous with the
peritoneum
– Term germinal epithelium
is a misnomer because
this layer does not give
rise to ova
• Outer cortex houses the
forming gametes
• Inner medullary region
contains the largest blood
vessels and nerves
STRUCTURE OF AN OVARY
OVARIES
• Embedded in the highly
vascular connective
tissue of the ovary
cortex are many saclike
structures called
ovarian follicles:
– Each consist of an
immature egg, called an
oocyte, encased by one
or more layers of
different cells:
• Surrounding cells are
called follicle cells if a
single layer is present
– Granulosa cells when
more than one layer is
present
STRUCTURE OF AN OVARY
OVARIES
•
Follicles at different stages of
maturation are distinguished
by their structure:
– Primordial follicle: one layer of
squamouslike follicle cells
surrounds the oocyte
– Primary follicle: has two or more
layers of cuboidal or columnartype granulosa cells enclosing the
oocyte
– Secondary follicle: when fluidfilled spaces form between the
granulosa cells of the Primary
Follicle, it is now a Secondary
Follicle
• Fluid –filled spaces coalesce to
form a central fluid-filled cavity
called an antrum
– Mature vesicular follicle
(Graafian follicle): bulges from
the surface of the ovary
OVARIES
• Each month in adult women,
one of the ripening follicles
ejects its oocyte from the
ovary, an event called
ovulation
• After ovulation, the ruptured
follicle is transformed into
the corpus luteum, which
eventually degenerates
• If pregnancy has occurred,
the corpus luteum continues
with a new role
STRUCTURE OF AN OVARY
OVULATION
The Female Duct System
Uterine Tubes
• The uterine tubes, or
fallopian tubes or
oviducts, form the
beginning of the
female duct system
– Receive the ovulated
oocyte
– Provide a site for
fertilization to take
place
POSTERIOR VIEW OF FEMALE
REPRODUCTIVE ORGANS
The Female Duct System
Uterine Tubes
•
Distal portion of the uterine tube
is expanded as it curves around
the ovary forming the ampulla
– Ends in a funnel-shaped
opening called the
infundibulum:
• Contains ciliated
projections called
fimbriae:
– Create current in the
peritoneal fluid that
tend to carry the
oocyte into the
uterine tube
– Fertilization usually occurs
in this area
POSTERIOR VIEW OF FEMALE
REPRODUCTIVE ORGANS
The Female Duct System
Uterine Tubes
• Each uterine tube
extends into the
superolateral region
of the uterus via a
constricted region
called the isthmus
The Female Duct System
Uterine Tubes
•
•
The uterine tube contains sheets
of smooth muscle, and its thick,
highly folded mucosa contains
both ciliated and nonciliated
cells
The oocyte is carried toward the
uterus by a combination of
muscular peristalsis and the
beating of the cilia
– Nonciliated cells of the mucosa
have dense microvilli and produce
a secretion that keeps the
oocyte (and sperm, if present)
moist and nourished
•
Externally, the uterine tubes are
covered by visceral peritoneum
and supported along their length
by a short mesentery (part of
the broad ligament) called the
mesosalpinx
POSTERIOR VIEW OF FEMALE
REPRODUCTIVE ORGANS
MIDSAGITTAL SECTION OF FEMALE PELVIS
SHOWING ORGANS OF FEMALE
REPRODUCTIVE SYSTEM
HOMEOSTATIC IMBALANCE
• The fact that the uterine tubes are not
continuous with the ovaries places
women at risk for ectopic pregnancy in
which ovum, fertilized in the peritoneal
cavity or distal portion of the fallopian
tube, begins developing there
– Such pregnancies naturally abort, often with
substantial bleeding
Ectopic Pregnancy
HOMEOSTATIC IMBALANCE
• Potential problem of infection from
other parts of the reproductive tract:
– Gonorrhea bacteria and other sexually
transmitted microorganisms sometimes infect
the peritoneal cavity causing an extremely
severe inflammation called pelvic
inflammatory disease (PID)
• If not treated: scarring of the narrow uterine
tubes and of the ovaries leading to sterility
UTERUS
•
•
•
•
•
•
Hollow, thick walled muscular organ
that functions to receive, retain, and
nourish a fertilized ovum
Size of a pear: larger in women who
have borne children
Body: major portion
Fundus: rounded region superior to
the entrance of the uterine tubes
Isthmus: slightly narrowed region
between the body and the cervix
Cervix: cervical canal
–
–
Communicates with the vagina
Mucosa of cervical canal contains
cervical glands that secrete a mucus
that fills the cervical canal
•
•
Presumably to block the spread of
bacteria from the vagina into the
uterus
Cervical mucus also blocks the entry
of sperm, except at midcycle, when it
becomes less viscous and allows
sperm to pass through
POSTERIOR VIEW OF FEMALE
REPRODUCTIVE ORGANS
MIDSAGITTAL SECTION OF FEMALE PELVIS
SHOWING ORGANS OF FEMALE
REPRODUCTIVE SYSTEM
HOMEOSTATIC IMBALANCE
• Cancer of the cervix:
– Causative risk include:
•
•
•
•
Frequent cervical inflammations
STDs
Multiple pregnancies
Virus: papillomavirus
– Pap smear is the most effective way to detect
this slow-growing cancer
• Remove some epithelia cells from cervical tip
Uterus Supports
• Supported:
– Laterally by the
mesometrium portion
of the broad ligament
– Inferiorly by the lateral
cervical ligaments
– Posteriorly by the
paired uterosacral
ligaments
– Anteriorly by the
fibrous round ligament
POSTERIOR VIEW OF FEMALE
REPRODUCTIVE ORGANS
ANTERIOR VIEW OF FEMALE
REPRODUCTIVE ORGANS
HOMEOSTASIS IMBALANCE
• Despite the many anchoring ligaments, the
principal support of the uterus is provided by
the muscles of the pelvic floor, namely the
muscles of the urogenital and pelvic
diaphragms
• These muscles are sometimes torn during
childbirth
• Subsequently, the supported uterus may sink
inferiorly, until the tip of the cervix protrudes
through the external vaginal opening
– This condition is called prolapse of the uterus
UTERINE WALL
•
Composed of three layers:
– Perimetrium: outermost serous
layer
• It is the visceral peritoneum
– Myometrium: bulky middle layer
• Composed of interlacing bundles
of smooth muscle
– Contract rhythmically during
childbirth to expel the baby from
the mother’s body
– Endometrium:
• Mucosal lining of the uterine cavity
• Simple columnar epithelium
underlain by a thick lamina propria
• If fertilization occurs, the young
embryo burrows (implants) and
resides here for the rest of
development
POSTERIOR VIEW OF FEMALE
REPRODUCTIVE ORGANS
ENDOMETRIUM AND ITS BLOOD SUPPLY
UTERINE WALL
ENDOMETRIUM
• Two chief strata:
– Stratum functionalis:
functional layer
• Undergoes cyclic changes in
response to blood levels of
ovarian hormones and is
shed during menstruation
(approximately every 28
days)
– Stratum basalis: deeper and
thinner
• Forms a new functionalis after
menstruation ends
• Unresponsive to ovarian
hormones
• Has numerous uterine
glands that change in length
as endometrial thickness
changes
ENDOMETRIUM AND ITS BLOOD SUPPLY
UTERINE WALL
ENDOMETRIUM
• To understand the
cyclic changes of the
uterine endometrium, it
is essential to
understand the
vascular supply of the
uterus
• Uterine arteries arise
from the internal iliacs in
the pelvis, ascend along
the side of the uterus,
and send branches into
the uterine wall
UTERINE WALL
ENDOMETRIUM
•
Uterine branches break up into
several arcuate arteries within
the myometrium sending radial
branches into the endometrium,
where they in turn give off
straight arteries to the stratum
basalis and spiral (coiled)
arteries to the stratum functionalis
– These spiral arteries repeatedly
degenerate and regenerate
– The spasms of these arteries
actually cause the functionalis
layer to be shed during
menstruation
•
Veins are thin-walled and form an
extensive network with occasional
sinusoidal enlargements
ENDOMETRIUM AND ITS BLOOD SUPPLY
VAGINA
• Thin-walled tube, 8-10 cm (3-4
inches) long
• Lies between the urinary
bladder and the rectum
• Extends from the cervix to
the body exterior
• Often called the birth canal
• Provides a passageway :
– For delivery of an infant
– For delivery of menstrual
blood
– Also receives the penis and
semen during sexual
intercourse (female organ of
copulation)
POSTERIOR VIEW OF FEMALE
REPRODUCTIVE ORGANS
MIDSAGITTAL SECTION OF FEMALE PELVIS
SHOWING ORGANS OF FEMALE
REPRODUCTIVE SYSTEM
VAGINA
• Distensible wall consists of three coats:
– Outer fibroelastic adventita
– Smooth muscle muscularis
– Inner mucosa marked by transverse ridges (rugae) which
stimulate the penis during intercourse
• Made of stratified squamous epithelium adapted to withstand
friction
• No glands, it is lubricated by cervical mucous glands
• Its epithelial cells release large amounts of glycogen, which is
anaerobically metabolized to lactic acid by resident bacteria
– Consequently the pH is normally quite acidic:
» Helps to keep the vagina healthy and free of infection, but it
is also hostile to sperm
» Although vaginal fluid of adult females is acidic, it tends to be
alkaline in adolescents, predisposing sexually active
teenagers to STDs
POSTERIOR VIEW OF FEMALE
REPRODUCTIVE ORGANS
MIDSAGITTAL SECTION OF FEMALE PELVIS
SHOWING ORGANS OF FEMALE
REPRODUCTIVE SYSTEM
VAGINA
•
In virgins (females who have
never participated in sexual
intercourse), the mucosa near
the distal vaginal orifice forms an
incomplete partition called the
hymen
– It is very vascular and tends to
bleed when it is ruptured during
the first coitus (sexual
intercourse):
• However, it may be ruptured
during sports activity, tampon
insertion, or pelvic examination
• Occasionally, it is so tough that
it must be breached surgically if
intercourse is to occur
•
Stretches considerably during
copulation and childbirth
EXTERNAL GENITALIA (VULVA)
OF THE FEMALE
EXTERNAL GENITALIA
•
Also called the vulva or
pudendum, includes the:
– Mons pubis:
• Fatty, rounded area overlying the
pubic symphysis
• After puberty, covered with pubic
hair
– Labia:
• Majora: larger lip folds
– Homologous to the male scrotum
(derived from the same
embryonic tissue)
– Contain pubic hair
– Enclose the labia minora
• Minora: smaller/thin lip folds
– Homologous to the ventral male
penis
– Hair-free
– Enclose a recess called the
vestibule
» Contains the openings
of the urethra more
anteriorly as well as that
of the vagina
EXTERNAL GENITALIA
• Vestibular glands: NOT
ILLUSTRATED
– Flank vaginal opening
– Homologous to the
bulbourethral gland in
males
– Release mucus into
vestibule and help to
keep it moist and
lubricated,
facilitating
intercourse
EXTERNAL GENITALIA
•
Clitoris: homologous to the male
penis
– Small, protruding structure,
composed largely of erectile
tissue
– Exposed portion is called the
glans:
• Hooded by a skin fold called
the prepuce of the clitoris,
formed by the junction of the
labia minora folds
• Richly innervated with
sensory nerve endings
sensitive to touch:
– Becomes swollen with
blood and erect during
tactile stimulation,
contributing to a
female’s sexual
arousal
EXTERNAL GENITALIA
• Perineum: dashed
lined area
– Soft tissues overlie the
muscles of the pelvic
region which support
the pelvic floor
Mammary Glands
• Are present in both sexes
but usually function only in
females to produce milk to
nourish a newborn baby
• Mammary glands are modified
sweat glands that are really
part of the integumentary
system
• Each mammary gland is
contained within a rounded
skin-covered breast within
the superficial fascia,
anterior to the pectoral
muscles of the thorax
Mammary Glands
• Slightly below the center of
each breast is a ring of
pigmented skin, the areola,
which surrounds a central
protruding nipple:
– Large sebaceous glands in
the areola make it slightly
bumpy and produce sebum
that reduces chapping and
cracking of the skin of the
nipple
– Autonomic nervous system
controls of smooth muscle
fibers in the areola and
nipple cause the nipple to
become erect when
stimulated by tactile or
sexual stimuli and when
exposed to cold
Mammary Glands
•
Internally, each mammary gland consists of
15 to 25 lobes that radiate around and open
at the nipple:
– The lobes are padded and separated
from each other by fibrous
connective tissue and fat
– Within the lobes are smaller units
called lobules:
• Contain glandular alveoli that
produce milk when a woman is
lactating:
– These alveolar glands
pass the milk into the
lactiferous ducts, which
open to the outside at the
nipple:
» Each duct has a
dilated region called
a lactiferous sinus
where milk
accumulates during
nursing
Mammary Glands
• Interlobar connective
tissue forms
suspensory
ligaments that
attach the breast to
the underlying
muscle fascia and to
the overlying dermis
– Natural support
for the breast
Mammary Glands
• In nonpregnant woman, the glandular
structure of the breast is largely
undeveloped and the duct system is
rudimentary; hence breast size is largely
due to the amount of fat deposits
Breast Cancer
• Usually arises from the epithelial cells of
the ducts, not from the alveoli
– Grows into a lump in the breast from which
cells eventually metastasize
• 70% have no known risk factor
– Early onset menses and late menopause
– No pregnancies or first pregnancy later in life
– Previous history of breast cancer
– Family history of breast cancer
FEMALE BREAST WITH
LACTATING MAMMARY GLANDS
Mammary Glands
• a: Normal breast
• b: Breast with tumor
MAMMOGRAM
PHYSIOLOGY OF THE FEMALE
REPRODUCTIVE SYSTEM
• Oogenesis is the production of female
gametes called oocytes, ova, or eggs
– A female’s total egg supply is determined at
birth and the time in which she releases them
extends from puberty to menopause (about
the age of 50)
• Total supply of eggs is already determined by
the time she is born
Oogenesis
•
•
Meiosis, the specialized nuclear division that occurs in the testes to
produce sperm, also occurs in the ovaries
– Female sex cells are produced, and the process is called
oogenesis
Process takes years to complete
– In the fetal period the diploid stem cells of the ovaries, the oogonia,
multiply rapidly by mitosis and, then enter a growth phase and lay in
nutrient reserves
– Gradually, primordial follicles begin to appear as the oogonia are
transformed into primary oocytes and become surrounded by a
single layer of flattened cells
– The primary oocytes begin the first meiotic division, but become
“stalled” late in prophase I and do not complete it
– By birth, a female has her lifetime supply of primary oocytes
• Of the original 7 million oocytes approximately 2 million of
them escape programmed death and are already in place in the
cortical region of the immature ovary
– Since they remain in their state of suspended animation all
through childhood, the wait is a long one—10 to 14 years
Oogenesis
•
•
At puberty, perhaps 400,000
oocytes remain and beginning at
this time a small number of primary
oocytes are activated each month
However, only one is selected each
time to continue meiosisI
– Producing a secondary oocyte
and a polar body:
• Polar body undergoes
meiosis II and produces two
polar bodies
• Secondary oocyte arrests
in metaphase II and it is
this cell that is ovulated
(not a functional ovum):
– If not fertilized by a
sperm, it deteriorates
– If penetrated by a
sperm, it quickly
completes meiosis II,
yielding one large
ovum and a tiny
second polar body
FLOWCHART OF MEIOTIC EVENTS
CORRELATED WITH FOLLICLE DEVELOPMENT
AND OVULATION IN THE OVARY
Oogenesis
• The unequal cytoplasmic divisions that occur
during oogenesis (I ovum and 3 polar bodies)
ensure that a functional egg has ample
nutrients for its seven-day journey to the
uterus
– Without nutrient-containing cytoplasm the
polar bodies degenerate and die
• Since the reproductive life of a female is at
best 40 years (11-51) and typically only one
ovulation occurs each month, fewer than 500
oocytes out of her estimated pubertal
potential of 400,000 are released during a
woman’s lifetime
FLOWCHART OF MEIOTIC EVENTS
CORRELATED WITH FOLLICLE DEVELOPMENT
AND OVULATION IN THE OVARY
PHYSIOLOGY OF THE FEMALE
REPRODUCTIVE SYSTEM
• The ovarian cycle is the monthly series
of events associated with the
maturation of the egg:
– The follicular phase is the period of follicle
growth typically lasting from day I to 14
– Ovulation occurs when the ovary wall
ruptures and the secondary oocyte is
expelled
– The luteal phase is the period of corpus
luteum activity, days 14-28
FLOWCHART OF MEIOTIC EVENTS
CORRELATED WITH FOLLICLE DEVELOPMENT
AND OVULATION IN THE OVARY
OVARIAN CYCLE
DEVELOPMENT AND FATE OF THE OVARIAN FOLLICLES
Ovarian Cycle
• Hormonal Regulation of the Ovarian Cycle:
– During childhood, the ovaries grow and secrete small
amounts of estrogen that inhibit the release of
gonadotropin-releasing hormone (GnRH) until
puberty, when the hypothalamus becomes less
sensitive to estrogen and begins to release GnRH in
a rhythmic manner
• The monthly series of events associated with the
maturation of an egg is called the ovarian cycle
– Two consecutive phases:
» Follicular phase: period of follicle growth (day 1-day 14)
» Luteal phase: period of corpus luteum activity (day 14-day
28)
– Ovulation occurring at mid-cycle
Ovarian Cycle
Follicular Phase
• Maturation of a primordial
follicle to the mature state
occupies the first half (day 1 day 14) of the cycle
• Primordial Follicle Becomes
a Primary Follicle:
– 1. The primordial follicles are
activated (process directed by
the oocyte), the squamouslike
cells surrounding the primary
oocyte grow, becoming
cuboidal cells, and the oocyte
enlarges
– 2. The follicle is now called
a primary follicle
Ovarian Cycle
Follicular Phase
•
•
Primary Follicle Becomes a
Secondary Follicle
3. Follicular cells proliferate,
forming a stratified epithelium
around the oocyte:
– As soon as more than one cell
layer is present, the follicle
cells take on the name
granulosa cells
• Granulosa cells and the
oocyte are connected by
gap junctions, through
which ions, metabolites,
and signaling chemicals
are passed between both
– They guide each
others development
– Oocyte grows
OVARIAN CYCLE
DEVELOPMENT AND FATE OF THE OVARIAN FOLLICLES
Ovarian Cycle
Follicular Phase
• 4. A layer of connective
tissue condenses around
the follicle, forming the
theca folliculi
• As the follicle grows, the thecal
and granulosa cells cooperate
to produce estrogen (inner
thecal cells produce
androgens, which the
granulosa cells convert to
estrogen)
– At the same time, the
granulosa cells secrete a
glycoprotein-rich sunstance
that forms a thick
transparent membrane,
called the zona pellucida,
around the oocyte
OVARIAN CYCLE
DEVELOPMENT AND FATE OF THE OVARIAN FOLLICLES
Ovarian Cycle
Follicular Phase
• 5. Clear liquid
accumulates between
the granulosa cells and
eventually coalesces to
form a fluid-filled cavity
the antrum
– The presence of an
antrum distinguishes
the new secondary
follicle from the
primary follicle
OVARIAN CYCLE
DEVELOPMENT AND FATE OF THE OVARIAN FOLLICLES
Ovarian Cycle
Follicular Phase
•
A Secondary Follicle Becomes a
Vesicular Follicle:
– The antrum continues to
expand with fluid until it
isolates the oocyte, along with
its surrounding capsule of
granulosa cells called a corona
radiata, on a stalk on one side of
the follicle
•
6. When a follicle is full size, it
becomes a vesicular follicle and
bulges from the external
ovarian surface:
– This usually occurs by day 14
– Primary oocyte completes
meiosis I to form the secondary
oocyte and first polar body
– Granulosa cells halt meiosis
– Stage is set for ovulation
Ovulation
• 7. Occurs when the ballooning ovary wall ruptures
and expels the secondary oocyte (still surrounded
by its corona radiata) into the peritoneal cavity:
– Some women experience a twinge of pain in the lower
abdomen when ovulation occurs
• Caused by the intense stretching of the ovarian wall during
ovulation
• There are always several follicles at different stages
of maturation but only one becomes the dominant
follicle
– The others degenerate and are reabsorbed
• In 1-2% of all ovulations, more than one oocyte is
ovulated:
– Can result in multiple births
Luteal Phase
• After ovulation, the
ruptured follicle collapses,
and the antrum fills with
clotted blood
– This corpus
hemorrhagicum is
eventually absorbed
– 8. The remaining
granulosa cells increase
in size and along with the
internal cells increase in
size and along with the
internal thecal cells they
form a new, quite
different endocrine
gland, the corpus luteum
Luteal Phase
• 8. Corpus luteum
(yellow body) begins to
secrete progesterone
and some estrogen
• 9. If pregnancy does not
occur, the corpus
luteum starts
degenerating in about
10 days and its
hormonal output ends
• 9. In this case, all that
ultimately remains is a
scar called the corpus
albicans (white body)
Luteal Phase
• If the oocyte is
fertilized and
pregnancy ensues,
the corpus luteum
persists until the
placenta is ready to
take over its
hormone-producing
duties in about 3
months
Hormonal Regulation of the
Ovarian Cycle
• During childhood, the ovaries grow and continuously
secrete small amounts of estrogens which inhibit
hypothalamic release of Gonadotropin-releasing
hormone (GnRH)
• As puberty nears, the hypothalamus becomes less
sensitive to estrogen and begins to release GnRH in a
rhythmic pulselike manner
• GnRH stimulates the anterior pituitary to release
Follicle Stimulating Hormone (FSH) and Luteinizing
Hormone (LH), which act on the ovaries
• Eventually 4-6 years the adult cyclic pattern is achieved
as GnRH levels continue to increase
Hormonal Interactions During the
Ovarian Cycle
• 1. On day 1 of the cycle,
rising levels of
Gonadotropin-releasing
hormone (GnRH) from
the hypothalamus
stimulates increased
production and release
of Follicle stimulating
hormone (FSH) and
Luteininzing hormone
(LH) by the anterior
pituitary
Hormonal Interactions During the
Ovarian Cycle
• 2. FSH and LH stimulate
follicle growth and maturation,
and estrogen secretion
• FSH exerts its main effects on
the follicle cells, whereas LH
(at least initially) targets the
thecal cells
• As the follicles enlarge, LH
prods the thecal cells to
produce androgens:
– These diffuse through the
basement membrane, where
they are converted to
estrogens by the granulosa
cells
FEEDBACK INTERACTIONS INVOLVED IN THE
REGULATION OF OVARIAN FUNCTION
Hormonal Interactions During the
Ovarian Cycle
• 3. Rising levels of
estrogen in the plasma
exert negative feedback
on the anterior pituitary,
inhibiting release of
FSH and LH
• Inhibin, released by the
granulosa cells, also
exerts negative
feedback controls on
FSH release during this
period
FEEDBACK INTERACTIONS INVOLVED IN THE
REGULATION OF OVARIAN FUNCTION
Hormonal Interactions During the
Ovarian Cycle
• 4. Although the initial
small rise in estrogen
blood levels inhibits the
hypothalamic-pituitary
axis, high estrogen
levels have the
opposite effect
• Once estrogen reaches
a critical blood
concentration, it exerts
positive feedback on
the brain and anterior
pituitary
FEEDBACK INTERACTIONS INVOLVED IN THE
REGULATION OF OVARIAN FUNCTION
Hormonal Interactions During the
Ovarian Cycle
• 5. High estrogen
levels exerts
positive feedback
on the anterior
pituitary resulting in
a burst of LH ( and,
to a lesser extent,
FSH)
FEEDBACK INTERACTIONS INVOLVED IN THE
REGULATION OF OVARIAN FUNCTION
Hormonal Interactions During the
Ovarian Cycle
• 6. The LH surge
stimulates the
primary oocyte of
the dominant follicle
to complete the first
meiotic division,
forming a secondary
oocyte that continues
on to metaphae II
Hormonal Interactions During the
Ovarian Cycle
• 6. LH also triggers
ovulation at or around
day 14
• Blood stops flowing
through the protruding
part of the follicle wall and
within 5 minutes, that
region of the follicle wall
bulges out, thins, and
then ruptures
– Role of FSH is still
unclear
• Shortly after ovulation,
estrogen levels decline
FEEDBACK INTERACTIONS INVOLVED IN THE
REGULATION OF OVARIAN FUNCTION
Hormonal Interactions During the
Ovarian Cycle
• 7. The LH surge also
transforms the ruptured
follicle into the corpus
luteum (hence the name:
luteinizing hormone), and
stimulates the newly
formed endocrine gland
to produce
progesterone and
estrogen almost
immediately after it is
formed
FEEDBACK INTERACTIONS INVOLVED IN THE
REGULATION OF OVARIAN FUNCTION
Hormonal Interactions During the
Ovarian Cycle
• 8. Rising plasma levels of
progesterone and estrogen
exert a powerful negative
feedback effect on anterior
pituitary release of LH and
FSH
– Corpus luteum release of
inhibin enhances this
inhibitory effect
• Declining gonadotropin
levels inhibit the
development of new follicles
and prevent additional LH
surges that might cause
additional oocytes to be
ovulated
Hormonal Interactions During the
Ovarian Cycle
• 8. As LH blood levels
fall, the stimulus for luteal
activity ends, and the
corpus luteum
degenerates:
– As goes the corpus
luteum, so go the levels
of ovarian hormones, and
blood estrogen and
progesterone levels drop
sharply
Hormonal Interactions During the
Ovarian Cycle
• The marked decline
in ovarian hormones
at the end of the
cycle (days 26-28)
ends their blockage
of FSH and LH
secretion, and the
cycle starts anew
Uterine (Menstrual) Cycle
• Although the uterus is where the young
embryo implants and develops, it is receptive
to implantation only for a very short period
each month
• Uterine (menstrual) cycle is a series of cyclic
changes that the uterine endometrium goes
through each month in response to changing
levels of ovarian hormones in the blood
– These endometrial changes are coordinated with
the phases of the ovarian cycle, which are
dictated by gonadotropins released by the
anterior pituitary
Uterine (Menstrual) Cycle
•
1. Days 1-5: Menstrual phase: (d)
– In this phase, menstruation, the
uterus sheds all but the deepest part
of its endometrium
• At the beginning of this stage,
ovarian hormones are at their
lowest normal levels and
gonadotropins are beginning to
rise
– Then FSH levels begin to
fall
– The thick functional layer of the
endometrium detaches from the uterine
wall, a process that is accompanied by
bleeding for 3-5 days
– The detached tissue and blood pass
out through the vagina as the
menstrual flow
– By day 5, the growing follicles are
starting to produce more estrogen
Uterine (Menstrual) Cycle
• 2. Days 6-14: The
Proliferation (preovulatory)
phase:
• Is the time in which the
endometrium is rebuilt once
again becoming velvety,
thick, and well vascularized
– Endometrium rebuilds itself
under the influence of rising
blood levels of estrogen
• The basal layer of the
endometrium generates a
new functional layer
– Estrogens induce synthesis of
progesterone receptors in the
endometrial cells, readying
them for interaction with
progesterone
Uterine (Menstrual) Cycle
• 2. Days 6-14: The
Proliferation
(preovulatory) phase:
– Normally, cervical mucus
is thick and sticky, but
rising estrogen levels
cause it to thin and
become crystalline,
forming channels that
facilitate the passage of
sperm into the uterus
Uterine (Menstrual) Cycle
• 2. Days 6-14: The
Proliferation
(preovulatory) phase:
– Ovulation:
• Takes less than 5 minutes
• Occurs in the ovary at the
end of the proliferative
stage (day 14) in
response to the sudden
release of LH from the
anterior pituitary
• LH also converts the
ruptured follicle to a
corpus luteum
Uterine (Menstrual) Cycle
• 3. Days 15-28:
Secretory
(postovulatory) phase:
– The endometrium
prepares for implantation
of an embryo
– Rising levels of
progesterone from the
corpus luteum act on the
estrogen-primed
endometrium, causing it
to prepare for
implantation
Uterine (Menstrual) Cycle
• 3. Days 15-28:
Secretory
(postovulatory) phase:
– Increasing progesterone
levels also cause the
cervical mucus to
become viscous again,
forming the cervical plug,
which blocks sperm
entry
– Rising progesterone (and
estrogen) levels inhibit
LH release by the
anterior pituitary
Uterine (Menstrual) Cycle
• If fertilization has not occurred, the corpus luteum begins to
degenerate toward the end of the secretory phase as LH blood
levels decline
• Progesterone levels fall, depriving the endometrium of hormonal
support, and the spiral arteries kink and go into spasms
• Denied oxygen and nutrients, the lysosmes of the ischemic
endometrial cells rupture, and the functional layer begins to
self-digest, setting the stage for menstruation to begin on day
28
• The spiral arteries constrict one final time and then suddenly
relax and open wide
– As blood gushes into the weakened capillary beds, they fragment,
causing the functional layer to slough off
• The menstrual cycle starts over again on this first day of
menstrual flow
Ovarian/Uterine Cycle
• Notice how the Ovarian and Uterine (Menstrual)
Cycles fit together
CORRELATION OF ANTERIOR PITUITARY AND
OVARIAN HORMONES WITH STRUCTURAL CHANGES
OF THE OVARIAN AND UTERINE CYCLES
CORRELATION OF ANTERIOR PITUITARY AND
OVARIAN HORMONES WITH STRUCTURAL CHANGES
OF THE OVARIAN AND UTERINE CYCLES
Extrauterine Effects of Estrogen and Progesterone
•
•
•
•
Rising estrogen levels promote oogenesis and follicle growth in the ovary, as
well a growth and function of the female reproductive structures
Estrogens supports the growth spurt at puberty that makes girls grow much more
quickly than boys during the ages of 12 and 13
– But his growth is short-lived because rising estrogen levels also cause the
epiphyses of the long bones to close sooner, and females reach their full
height between the ages of 15 and 17 years
• In contrast, the aggressive growth of males continues until the age of 19 to
21 years
The estrogen-induced secondary sex characteristics of females include:
– Growth of breasts
– Increased deposition of subcutaneous fat in the hips and breast
– Widening and lightening of the pelvis
– Growth of pubic and axillary hair
– Metabolic changes:
• Maintaining low total blood cholesterol levels (and high HDL levels)
• Facilitating calcium uptake, helping sustain the density of the skeleton
Progesterone works with estrogen to establish and help regulate the uterine
cycle, and promotes changes in cervical mucus
PHYSIOLOGY OF THE FEMALE
REPRODUCTIVE SYSTEM
• In the female sexual response:
– The clitoris, vaginal mucosa, and breasts become engorged with
blood
– The nipples erect
– Vestibular glands lubricate the vestibule and facilitates entry of the
penis increase in activity
– The final phase is orgasm:
•
•
•
•
Muscular tension increases throughout the body
Pulse rate and blood pressure rise
Uterus contracts rhythmically
Not followed by a refractory period (as in males):
– So females may experience multiple orgasm during a single sexual
experience
• A male must achieve orgasm and ejaculate if fertilization is to
occur, but female orgasm is not required for conception
– Some women never experience orgasm, yet are perfectly able to
conceive
SEXUALLY TRANSMITTED DISEASES (STDs)
VENEREAL DISEASES (VDs)
• Gonorrhea is caused by Neisseria gonorrhoeae bacteria, which
invade the mucosae of the reproductive and urinary tracts
• Spread by contact with genital, anal, and pharyngeal mucosal
surfaces
• Commonly called the “clap”
• Most frequent symptom in males is urethritis, accompanied by
painful urination and discharge of pus from the penis
• Symptoms vary in females, ranging from none (20%) to abdominal
discomfort, vaginal discharge, abnormal uterine bleeding, and
occasionally, urethral symptoms similar to those seen in males
• Untreated:
– Urethral constriction and inflammation of the urinary system
– In women, it causes pelvic inflammatory disease and sterility
• Strains resistant to antibiotics are becoming increasingly
prevalent
SEXUALLY TRANSMITTED DISEASES (STDs)
VENEREAL DISEASES (VDs)
• Syphilis is caused by Treponema pallidum, a
bacteria that easily penetrate intact mucosae and
abraded (worn by friction/irritated) skin, and enter
the lymphatics and the bloodstream
– Within a few hours of exposure, an asymptomatic (without
symptoms) bodywide infection is in progress
– Incubation period is typically 2-3 weeks, at the end of which a
red, painless primary lesion called a chancre appears at the site
of bacterial invasion
• Primary lesion ulcerates and becomes crusty; then it heals
spontaneously and disappears after one to a few weeks
• Can be contracted congenitally from an infected
mother:
– Fetuses infected with syphilis are usually stillborn or die
shortly after birth
SEXUALLY TRANSMITTED DISEASES (STDs)
VENEREAL DISEASES (VDs)
• Syphilis: if untreated:
– Secondary signs appear several weeks later but
disappear spontaneously in 3-12 weeks
• Pink skin rash all over the body is one of the first symptoms
• Fever and joint pain are common
– Then the disease enters the latent period
• Detectable only in blood test
• May last a lifetime
• May be killed by the immune system
– May be followed by tertiary syphilis
• Characterized by gummas
– Destructive lesions of the CNS, blood vessels, bones, and skin
• Treatment: antibiotics
SEXUALLY TRANSMITTED DISEASES (STDs)
VENEREAL DISEASES (VDs)
• Chlamydia is the most common sexually transmitted disease in the
U.S. and is caused by the bacteria Chlamydia trachomatis
– Bacteria with viruslike dependence on host cells
– Incubation period about one week
– Symptoms:
• Male:
–
–
–
–
–
Urethritis (painful, frequent urination and thick penile discharge)
Rectal or testicular pain
Painful intercourse
Arthritis
Urogenital tract infection
• Female:
–
–
–
–
–
–
80% no symptoms
Vaginal discharge
Abdominal , rectal pain
Painful intercourse
Irregular menses
sterility
SEXUALLY TRANSMITTED DISEASES (STDs)
VENEREAL DISEASES (VDs)
• Chlamydia:
– Largely unrecognized, silent epidemic that infects 4-5 million
people yearly
• Most common sexually transmitted disease in the U.S.
• Responsible for:
– 25-50% of all diagnosed cases of pelvic inflammatory disease
– 1 in 4 chance of ectopic pregnancy
– Each year more than 150,000 infants are born to infected mothers
» Newborns infected in the birth canal tend to develop conjunctivitis
and respiratory tract inflammations including pneumonia
– 20% of males and 30% of females infected with gonorrhea are also
infected by Chlamydia trachomatis, the causative agent of Chlamydia
– Treatment: antibiotics
SEXUALLY TRANSMITTED DISEASES (STDs)
VENEREAL DISEASES (VDs)
• Genital warts are caused by a group of about 60 viruses
known as the human papillomavirus (HPV)
– Responsible for the sexual transmission of genital warts
– About 1 million Americans infected each year
– Increases the risk for certain cancers
•
•
•
•
Penile
Vaginal
Cervical
Anal
• Treatment:
– Difficult and controversial:
• Some prefer to leave the warts untreated unless they become
widespread
• Many recommend wart removal by cryosurgery or laser therapy
GENITAL WARTS
SEXUALLY TRANSMITTED DISEASES (STDs)
VENEREAL DISEASES (VDs)
•
Genital herpes is generally caused by the herpes simplex virus type 2
(Epstein-Barr virus), which is transferred via infectious secretions
– Most difficult human pathogen to control
– Remain silent for weeks or years and then suddenly flare up, causing a burst of
blisterlike lesions
– Painful lesions that appear on the reproductive organs
– Congenital herpes infections can cause severe malformations of a fetus
– Has been leaked to cervical cancer
– Most people who have genital herpes do not know it, and it has been estimated
that ¼ to ½ of all Americans harbor the type-2 herpes simplex virus
•
Treatment:
– Antiviral acyclovir: speeds healing of the lesions and reduces the frequency of
flare-ups
– Inter Vir-A: antiviral ointment, provides some relief from the itching and pain that
accompany the lesions
DEVELOPMENTAL ASPECTS OF THE
REPRODUCTIVE SYSTEM: CHRONOLOGY OF
SEXUAL DEVELOPMENT
• Embryological and Fetal Events
– Sex is determined by the sex
chromosomes at conception; females
have two X chromosomes and males have
an X and a Y chromosome
• A single gene on the Y chromosome—the SRY
gene—initiates testes development and hence
maleness
– Thus, the father determines the genetic sex of the
offspring
HOMEOSTATIC IMBALANCE
• Nondisjunction during meiosis
– Abnormal combinations of sex chromosomes
• Female XO: Turner’s syndrome
– Never develop ovaries
• Male YO: die during embryonic development
• Female XXX: normal intelligence
– Four or more X chromosomes
» Mentally retarded and underdeveloped ovaries and limited fertility
• Male XXY: Klinefelter’s syndrome
–
–
–
–
1 out of 500 live male births
Most common sex chromosome abnormality
Sterile
Normal intelligence but, the incidence of mental retardation increases
as the number of X sex chromosomes rises
» One Y but three or more X’s
HOMEOSTATIC IMBALANCE
• Probably the most striking male-female meiotic
difference is the fact that spermatogenesis stops
when faced with meiotic disruption, whereas
female meiosis marches on
• Hence, female meiosis I seems to be
especially error prone
– Of the 10-25 % of human fetuses that have the wrong
number of chromosomes, some 80-90% result from
nondisjunction during meiosis I of the female
DEVELOPMENTAL ASPECTS OF THE
REPRODUCTIVE SYSTEM: CHRONOLOGY OF
SEXUAL DEVELOPMENT
• Sexual Differentiation of the Reproductive
System
– The gonads of both males and females begin
to develop during week 5 of gestation
– During week 7 the gonads begin to become
testes in males, and in week 8 they begin to
form ovaries in females
– The external genitalia arise from the same
structures in both sexes, with
differentiation occurring in week 8
EMBRYONIC DEVELOPMENT OF
INTERNAL REPRODUCTIVE ORGANS
EMBRYONIC DEVELOPMENT OF
EXTERNAL GENITALIA
HOMEOSTATIC IMBALANCE
•
•
•
•
Any interference with the normal pattern of sex hormone production in
the embryo results in bizarre abnormalities
– If the embryonic testes do not produce testosterone, a genetic male
develops the female accessory structures and external genitalia
– If the testes fail to produce AMH (causes the breakdown of the
paramesonephric ducts which give rise to the female duct system:
oviducts and uterus) both the female and male duct systems form, but
the external genitalia are those of the male
– If a genetic female is exposed to testosterone (if mother has an
androgen-producing tumor of the adrenal gland or uses testosterone),
the embryo has ovaries but develops the male ducts and glands, as well
as a penis and an empty scrotum
It appears that the female pattern of reproductive structures has an
intrinsic ability to develop and in the absence of testosterone it
proceeds to do so, regardless of the embryo’s genetic makeup
Individual’s with accessory reproductive structures that do not “match” their
gonads are called pseudohermaphrodites
– Many seek sex-change operations to match their outer selves
(external genitalia) with their inner selves (gonads)
True hermaphrodites are rare and possess both ovarian and testicular
tissue
DEVELOPMENTAL ASPECTS OF THE
REPRODUCTIVE SYSTEM: CHRONOLOGY OF
SEXUAL DEVELOPMENT
• About two months before birth the
testes begin their descent toward the
scrotum, dragging their nerve supply
and blood supply with them
DESCENT OF THE TESTES
DEVELOPMENTAL ASPECTS OF THE
REPRODUCTIVE SYSTEM: CHRONOLOGY OF
SEXUAL DEVELOPMENT
• Puberty is the period of life, generally
between the ages of 10 and 15 years,
when the reproductive organs grow to
adult size and become functional
• Ovarian function declines gradually with
age; menstrual cycles become more
erratic and shorter until menopause, when
ovulation and menstruation stop entirely
Menopause
•
•
•
•
Normally occurs between the ages of 46 and 54 years
Considered to have occurred when a whole year passes without menstruation
Although ovarian estrogen production continues for a while after menopause, the
ovaries finally stop functioning as endocrine organs
Without sufficient estrogen the reproductive organs and breasts begin to
atrophy, the vagina becomes dry, and vaginal infections become increasingly
common
– Other sequels due to the lack of estrogen include irritability and
depression (in some); intense vasodilation of the skin’s blood vessels,
which causes uncomfortable sweat-drenching “hot flashes”; gradual
thinning of the skin and loss of bone mass
– Slowly rising total blood cholesterol levels and falling HDL levels place
postmenopausal women at risk for cardiovascular disorders
– Some physicians prescribe low-dose estrogen-progesterone preparations to
help women through this often difficult period and to prevent the skeletal and
cardiovascular complications
– HOWEVER, there is still controversy about whether the estrogen component
increases the risk of breast cancer in postmenopausal women and the
cardiovascular benefits hoped for are questionable at best