Transcript ch_27_lecture_outline_b

CHAPTER # 27(b)
THE REPRODUCTIVE
SYSTEM
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Hormonal Regulation of Male Reproductive
Function
• A sequence of hormonal regulatory events
involving the hypothalamus, anterior pituitary
gland, and the testes
• The hypothalamic-pituitary-gonadal (HPG) axis
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HPG Axis
1. Hypothalamus releases gonadotropinreleasing hormone (GnRH)
2. GnRH stimulates the anterior pituitary to
secrete FSH and LH
3. FSH causes sustentacular cells to release
androgen-binding protein (ABP), which
makes spermatogenic cell receptive to
testosterone
4. LH stimulates interstitial cells to release
testosterone
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HPG Axis
5. Testosterone is the final trigger for
spermatogenesis
6. Feedback inhibition on the hypothalamus
and pituitary results from
• Rising levels of testosterone
• Inhibin (released when sperm count is high)
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1
GnRH
Anterior
pituitary
8
Via portal
blood
7
2
Inhibin
FSH
3
2
LH
4
Interstitial
cells
Testosterone
Sustentacular
cell
Spermatogenic
cells
Seminiferous
tubule
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6
5
Somatic and
psychological
effects at
other body
sites
Stimulates
Inhibits
Figure 27.9
Mechanism and Effects of Testosterone
Activity
• Testosterone
• Synthesized from cholesterol
• Transformed to exert its effects on some target
cells
• Dihydrotestosterone (DHT) in the prostate
• Estrogen in some neurons in the brain
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Mechanism and Effects of Testosterone
Activity
• Prompts spermatogenesis
• Targets all accessory organs; deficiency leads
to atrophy
• Has multiple anabolic effects throughout the
body
• Is the basis of the sex drive (libido) in males
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Male Secondary Sex Characteristics
• Features induced in the nonreproductive
organs by male sex hormones (mainly
testosterone)
• Appearance of pubic, axillary, and facial hair
• Enhanced growth of the chest and deepening
of the voice
• Skin thickens and becomes oily
• Bones grow and increase in density
• Skeletal muscles increase in size and mass
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Female Reproductive Anatomy
• Ovaries: female gonads
• Produce female gametes (ova)
• Secrete female sex hormones (estrogen and
progesterone)
• Accessory ducts include
• Uterine tubes
• Uterus
• Vagina
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Female Reproductive Anatomy
• Internal genitalia
• Ovaries
• Uterine tubes
• Uterus
• Vagina
• External genitalia
• The external sex organs
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Suspensory
ligament of
ovary
Peritoneum
Uterosacral
ligament
Perimetrium
Rectouterine
pouch
Rectum
Posterior fornix
Cervix
Anterior fornix
Vagina
Anus
Urogenital diaphragm
Greater vestibular
(Bartholin’s) gland
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Infundibulum
Uterine tube
Ovary
Fimbriae
Uterus
Round ligament
Vesicouterine
pouch
Urinary bladder
Pubic symphysis
Mons pubis
Urethra
Clitoris
External urethral
orifice
Hymen
Labium minus
Labium majus
Figure 27.10
Ovaries
• Held in place by several ligaments
• Ovarian ligament: anchors ovary medially to
the uterus
• Suspensory ligament: anchors ovary laterally
to the pelvic wall
• Mesovarium: suspends the ovary
• Broad ligament: supports the uterine tubes,
uterus, and vagina; also contains the
suspensory ligament and the mesovarium
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Suspensory
ligament of ovary
Ovarian blood
vessels
Uterine (fallopian) tube
Mesosalpinx
Mesovarium
Broad
ligament
Mesometrium
Ovarian ligament
Body of uterus
Ureter
Uterine blood vessels
Isthmus
Uterosacral ligament
Lateral cervical
(cardinal) ligament
Lateral fornix
Cervix
(a)
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Fundus
of uterus
Ovary
Lumen (cavity)
of uterus
Uterine
tube
Ampulla
Isthmus
Infundibulum
Fimbriae
Round ligament of uterus
Endometrium
Wall of uterus
Myometrium
Perimetrium
Internal os
Cervical canal
External os
Vagina
Figure 27.12a
Ovaries
• Blood supply: ovarian arteries and the ovarian
branch of the uterine artery
• Surrounded by a fibrous tunica albuginea
• Two poorly defined regions
• Cortex: ovarian follicles
• Medulla: large blood vessels and nerves
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Ovaries
• Follicle
• Immature egg (oocyte) surrounded by
• Follicle cells (one cell layer thick)
• Granulosa cells (when more than one layer
is present)
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Follicles
• Several stages of development
• Primordial follicle: squamouslike follicle cells +
oocyte
• Primary follicle: cuboidal or columnar follicle
cells + oocyte
• Secondary follicle: two or more layers of
granulosa cells + oocyte
• Late secondary follicle: contains fluid-filled
space between granulosa cells; coalesces to
form a central antrum
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Ovaries
• Vesicular (Graafian) follicle
• Fluid-filled antrum forms; follicle bulges from
ovary surface
• Ovulation
• Ejection of the oocyte from the ripening follicle
• Corpus luteum develops from ruptured follicle
after ovulation
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Tunica
albuginea
Degenerating corpus
luteum (corpus
albicans)
Germinal
epithelium
Primary
follicles
Ovarian
ligament
Cortex
Oocyte
Granulosa cells
Late secondary follicle
Mesovarium and
blood vessels
Vesicular
(Graafian)
follicle
Antrum
Oocyte
Zona
pellucida
Theca
folliculi
Ovulated
oocyte
Corpus luteum
Corona
Developing
radiata
corpus luteum
(a) Diagrammatic view of an ovary sectioned to reveal the follicles in its interior
Medulla
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Figure 27.11a
Female Duct System
• Uterine (fallopian) tubes or oviducts
• Uterus
• Vagina
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Uterine Tubes
• Ampulla
• Distal expansion with infundibulum near ovary
• Usual site of fertilization
• Ciliated fibriae of infundibulum create currents
to move oocyte into uterine tube
• Isthmus: constricted region where tube joins
uterus
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Uterine Tubes
• Oocyte is carried along by peristalsis and
ciliary action
• Nonciliated cells nourish the oocyte and the
sperm
• Mesosalpinx: mesentery that supports the
uterine tubes
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Suspensory
ligament of ovary
Ovarian blood
vessels
Uterine (fallopian) tube
Mesosalpinx
Mesovarium
Broad
ligament
Mesometrium
Ovarian ligament
Body of uterus
Ureter
Uterine blood vessels
Isthmus
Uterosacral ligament
Lateral cervical
(cardinal) ligament
Lateral fornix
Cervix
(a)
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Fundus
of uterus
Ovary
Lumen (cavity)
of uterus
Uterine
tube
Ampulla
Isthmus
Infundibulum
Fimbriae
Round ligament of uterus
Endometrium
Wall of uterus
Myometrium
Perimetrium
Internal os
Cervical canal
External os
Vagina
Figure 27.12a
Uterus
• Body: major portion
• Fundus: rounded superior region
• Isthmus: narrowed inferior region
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Uterus
• Cervix: narrow neck, or outlet; projects into
the vagina
• Cervical canal communicates with the
• Vagina via the external os
• Uterine body via the internal os
• Cervical glands secrete mucus that blocks
sperm entry except during midcycle
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Supports of the Uterus
• Mesometrium—lateral support: portion of the
broad ligament
• Lateral cervical (cardinal) ligaments: from the
cervix and superior part of the vagina to the
walls of the pelvis
• Uterosacral ligaments secure uterus to the
sacrum
• Round ligaments bind to the anterior wall
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Suspensory
ligament of ovary
Ovarian blood
vessels
Uterine (fallopian) tube
Mesosalpinx
Mesovarium
Broad
ligament
Mesometrium
Ovarian ligament
Body of uterus
Ureter
Uterine blood vessels
Isthmus
Uterosacral ligament
Lateral cervical
(cardinal) ligament
Lateral fornix
Cervix
(a)
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Fundus
of uterus
Ovary
Lumen (cavity)
of uterus
Uterine
tube
Ampulla
Isthmus
Infundibulum
Fimbriae
Round ligament of uterus
Endometrium
Wall of uterus
Myometrium
Perimetrium
Internal os
Cervical canal
External os
Vagina
Figure 27.12a
Peritoneal Pouches
• Sacs of peritoneum exist around the uterus
• Vesicouterine pouch is between bladder and
uterus
• Rectouterine pouch is between rectum and
uterus
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Uterine Wall
• Three layers
1. Perimetrium: serous layer (visceral
peritoneum)
2. Myometrium: interlacing layers of smooth
muscle
3. Endometrium: mucosal lining
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Endometrium
• Stratum functionalis (functional layer)
• Changes in response to ovarian hormone
cycles
• Is shed during menstruation
• Stratum basalis (basal layer)
• Forms new functionalis after menstruation
• Unresponsive to ovarian hormones
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Uterine Vascular Supply
• Uterine arteries: arise from internal iliacs
• Arcuate arteries: in the myometrium
• Radial branches in the endometrium branch
into
• Spiral arteries  stratum functionalis
• Straight arteries  stratum basalis
• Spasms of spiral arteries leads to shedding of
stratum functionalis
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Lumen of uterus
Epithelium
Capillaries
Uterine glands
Venous sinusoids
Lamina propria of
connective tissue
Spiral (coiled) artery
Straight artery
Endometrial vein
Smooth muscle fibers
Radial artery
Arcuate artery
Uterine artery
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(b)
Figure 27.13b
Vagina
• Birth canal and organ of copulation
• Extends between the bladder and the rectum
from the cervix to the exterior
• Urethra embedded in the anterior wall
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Vagina
• Layers of wall
1. Fibroelastic adventitia
2. Smooth muscle muscularis
3. Stratified squamous mucosa with rugae
• Mucosa near the vaginal orifice forms an
incomplete partition called the hymen
• Vaginal fornix: upper end of the vagina
surrounding the cervix
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Mons
pubis
Prepuce
of clitoris
Clitoris
(glans)
Vestibule
Labia
majora
Labia
minora
Urethral
orifice
Hymen
(ruptured)
Vaginal
orifice
Anus
(a)
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Opening of the duct
of the greater
vestibular gland
Figure 27.14a
External Genitalia (Vulva or Pudendum)
• Mons pubis: fatty area overlying pubic
symphysis
• Labia majora: hair-covered, fatty skin folds
• Labia minora: skin folds lying within labia
majora
• Vestibule: recess between labia minora
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External Genitalia
• Greater vestibular glands
• Homologous to the bulbourethral glands
• Release mucus into the vestibule for
lubrication
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External Genitalia
• Clitoris
• Erectile tissue hooded by a prepuce
• Glans clitoris: exposed portion
• Perineum
• Diamond-shaped region between the pubic
arch and coccyx
• Bordered by the ischial tuberosities laterally
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Clitoris
Labia minora
Labia majora
Inferior ramus of pubis
Pubic symphysis
Anus
Body of clitoris,
containing corpora
cavernosa
Clitoris (glans)
Crus of clitoris
Urethral orifice
Vaginal orifice
(b)
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Bulb of
vestibule
Fourchette
Greater
vestibular
gland
Figure 27.14b
Mammary Glands
• Modified sweat glands consisting of 15–25
lobes
• Areola: pigmented skin surrounding the nipple
• Suspensory ligaments: attach the breast to
underlying muscle
• Lobules within lobes contain glandular alveoli
that produce milk
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Mammary Glands
• Milk  lactiferous ducts  lactiferous sinuses
 open to the outside at the nipple
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First rib
Skin (cut)
Pectoralis major muscle
Suspensory ligament
Adipose tissue
Lobe
Areola
Nipple
Opening of
lactiferous duct
Lactiferous sinus
(a)
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Lactiferous duct
Lobule containing
alveoli
Hypodermis
(superficial fascia)
Intercostal muscles
(b)
Figure 27.15
Breast Cancer
• Usually arises from the epithelial cells of small
ducts
• Risk factors include:
• Early onset of menstruation and late
menopause
• No pregnancies or first pregnancy late in life
• Family history of breast cancer
• 10% are due to hereditary defects, including
mutations to the genes BRCA1 and BRCA2
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Breast Cancer: Detection and Treatment
• 70% of women with breast cancer have no
known risk factors
• Early detection via self-examination and
mammography
• Treatment depends upon the characteristics
of the lesion:
• Radiation, chemotherapy, and surgery
followed by irradiation and chemotherapy
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(a) Mammogram procedure
Malignancy
(b) Film of normal breast
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(c) Film of breast with tumor
Figure 27.16
Oogenesis
• Production of female gametes
• Begins in the fetal period
• Oogonia (2n ovarian stem cells) multiply by
mitosis and store nutrients
• Primary oocytes develop in primordial follicles
• Primary oocytes begin meiosis but stall in
prophase I
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Oogenesis
• Each month after puberty, a few primary
oocytes are activated
• One is selected each month to resume
meiosis I
• Result is two haploid cells
• Secondary oocyte
• First polar body
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Oogenesis
• The secondary oocyte arrests in metaphase II
and is ovulated
• If penetrated by sperm the second oocyte
completes meiosis II, yielding
• Ovum (the functional gamete)
• Second polar body
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Follicle development
in ovary
Meiotic events
Before birth
Oogonium (stem cell)
Follicle cells
Oocyte
Mitosis
Primary oocyte
Primordial follicle
Primary oocyte
(arrested in prophase I;
present at birth)
Primordial follicle
Growth
Infancy and
childhood
(ovary inactive)
Each month from
puberty to
menopause
Primary follicle
Primary oocyte (still
arrested in prophase I)
Secondary follicle
Spindle
Meiosis I (completed
by one primary oocyte
each month in response
to LH surge)
First polar body
Meiosis II of polar
body (may or may
not occur)
Polar bodies
(all polar bodies
degenerate)
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Vesicular (Graafian)
follicle
Secondary oocyte
(arrested in
metaphase II)
Ovulation
Sperm
Second
Ovum
polar body
Meiosis II
completed
(only if
sperm
penetration
occurs)
Degenating
Ovulated secondary
oocyte
In absence of
fertilization, ruptured
follicle becomes a
corpus luteum and
ultimately degenerates.
corpus luteum
Figure 27.17
Ovarian Cycle
• Monthly series of events associated with the
maturation of an egg
• Two consecutive phases (in a 28-day cycle)
• Follicular phase: period of follicle growth
(days 1–14)
• Ovulation occurs midcycle
• Luteal phase: period of corpus luteum activity
(days 14–28)
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Follicular Phase
• Primordial follicle becomes primary follicle
1. The primordial follicle is activated
• Squamouslike cells become cuboidal
2. Follicle enlarges to become a primary (1)
follicle
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Theca folliculi
3
2
4
1
5
6
8
7
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Primary oocyte
Zona pellucida
Antrum
Secondary
oocyte
Secondary oocyte
Corona radiata
1
Primordial
follicles
Figure 27.18 (1 of 7)
Theca folliculi
3
2
4
1
5
6
8
7
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Primary oocyte
Zona pellucida
Antrum
Secondary
oocyte
Secondary oocyte
Corona radiata
2
Primary
follicle
Figure 27.18 (2 of 7)
Follicular Phase
3. Primary follicle becomes a secondary follicle
• Stratified epithelium (granulosa cells)
forms around oocyte
• Granulosa cells and oocyte guide one
another’s development
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Follicular Phase
4. Secondary follicle becomes a late secondary
follicle
• Connective tissue (theca folliculi) and
granulosa cells cooperate to produce
estrogens
• Zona pellucida forms around the oocyte
• Fluid begins to accumulate
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Theca folliculi
3
2
4
1
5
6
8
7
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Primary oocyte
Zona pellucida
Antrum
Secondary
oocyte
Secondary oocyte
Corona radiata
3
Secondary
follicle
Figure 27.18 (3 of 7)
Theca folliculi
3
2
4
1
5
6
8
7
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Primary oocyte
Zona pellucida
Antrum
Secondary
oocyte
Secondary oocyte
Corona radiata
4
Late secondary
follicle
Figure 27.18 (4 of 7)
Follicular Phase
5. Late secondary follicle becomes a vesicular
follicle
• Antrum forms and expands to isolate the
oocyte with its corona radiata on a stalk
• Vesicular follicle bulges from the external
surface of the ovary
• The primary oocyte completes meiosis I
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Ovulation
• Ovary wall ruptures and expels the secondary
oocyte with its corona radiata
• Mittelschmerz: twinge of pain sometimes felt
at ovulation
• 1–2% of ovulations release more than one
secondary oocyte, which, if fertilized, results
in fraternal twins
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Theca folliculi
3
2
4
1
5
6
8
7
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Primary oocyte
Zona pellucida
Antrum
Secondary
oocyte
Secondary oocyte
Corona radiata
5
Mature vesicular
follicle carries out
meiosis I; ready to
be ovulated
Figure 27.18 (5 of 7)
Theca folliculi
3
2
4
1
6
8
7
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Primary oocyte
Zona pellucida
Antrum
Secondary
5
oocyte
6 Follicle ruptures;
secondary oocyte
Secondary oocyte
Corona radiata
ovulated
Figure 27.18 (6 of 7)
Luteal Phase
• Ruptured follicle collapses
• Granulosa cells and internal thecal cells form
corpus luteum
• Corpus luteum secretes progesterone and
estrogen
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Luteal Phase
• If no pregnancy, the corpus luteum
degenerates into a corpus albicans in 10 days
• If pregnancy occurs, corpus luteum produces
hormones until the placenta takes over at
about 3 months
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Theca folliculi
3
2
4
1
6
8
7
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Primary oocyte
Zona pellucida
Antrum
Secondary
5
oocyte
7 Corpus luteum
(forms from
Secondary oocyte
ruptured follicle)
Corona radiata
Figure 27.18 (7 of 7)
Establishing the Ovarian Cycle
• During childhood, ovaries grow and secrete
small amounts of estrogens that inhibit the
hypothalamic release of GnRH
• As puberty nears, GnRH is released; FSH and
LH are released by the pituitary, and act on
the ovaries
• These events continue until an adult cyclic
pattern is achieved and menarche occurs
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