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Chapter 28
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Female Reproductive System
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Reproductive Anatomy
Puberty and Menopause
Oogenesis and the Sexual Cycle
Female Sexual Response
Pregnancy and Childbirth
Lactation
28-2
Female Reproductive System
• Produce and
deliver
gametes
• Provide
nutrition and
room for fetal
development
• Give birth
• Nourish infant
28-3
Sex Differentiation
• Male and female are indistinguishable for
first 8 to 10 weeks of development
• Female develops
– no testosterone or müllerian-inhibiting factor
• causes degeneration of (male) mesonephric duct
– paramesonephric duct
• develops into uterine tubes, uterus and vagina
– genital tubercle becomes clitoris
– urogenital folds develop into labia minora
– labioscrotal folds into labia majora
28-4
Ovary
• Produces eggs and hormones
– almond-shaped, 3 cm x 1.5 cm x 1 cm
– tunica albuginea capsule like on testes
– cortex produces gametes; medulla holds vessels
• Each egg develops in its own fluid-filled follicle
and is released by ovulation
• Ligaments
– attached to uterus by ovarian ligament
– attached to pelvic wall by suspensory ligament
• contains ovarian artery, vein and nerves
– anchored to broad ligament by mesovarium
28-5
Anatomy of Ovary
28-6
Secondary Sex Organs
• Internal genitalia
– duct system of uterine tubes, uterus,
vagina
• External genitalia
– clitoris, labia minora, and labia majora
– occupy perineum
– accessory glands beneath skin provide
lubrication
28-7
Uterine (Fallopian) Tubes
• 10 cm long, muscular tube
lined with ciliated cells
• Major portions
– narrow isthmus near uterus
– body (ampulla): middle
portion
– flares distally into
infundibulum
with fimbriae
• Enclosed in superior
margin of broad
ligament (mesosalpinx)
28-8
Epithelial Lining of Uterine Tube
28-9
Uterus
• Thick-walled, pear-shaped muscular chamber that opens
into vagina and tilts forward over urinary bladder
– internal and external os of cervical canal
– openings into uterine tubes in two upper corners
• Domed fundus above body of organ
28-10
Reproductive Tract with Ligaments
28-11
Histology of Uterine Wall
• Perimetrium - external serosa layer
• Myometrium - middle muscular layer
– 1.25 cm thick in nonpregnant uterus
– smooth muscle
• produces labor contractions, expels fetus
• Endometrium
– simple columnar epithelium with thick layer
compound tubular glands
• stratum functionalis – superficial, shed each period
• stratum basalis - deep layer, regenerates a new
stratum functionalis with each menstrual cycle 28-12
Normal/Abnormal PAP Smears
28-13
Vessels of Reproductive Tract
Hormonal changes cause spiral artery
vasoconstriction, necrosis of stratum functionalis and
menstrual flow
28-14
Ligaments of Reproductive Tract
28-15
Vagina
• 8-10 cm distensible muscular tube
– allows for discharge of menstrual fluid, receipt of
penis, semen and birth of baby
• Outer adventitia, middle muscularis and inner
mucosa
• Epithelium
– child - simple cuboidal
– puberty - estrogens transform to stratified squamous
• bacteria ferment glycogen rich cells producing acidic pH
• Tilted posteriorly between rectum and urethra
– urethra embedded in its anterior wall
28-16
Vulva (Pudendum)
• Mons pubis - mound of fat over pubic
symphysis; covered by pubic hair
• Labia majora - thick folds of skin
• Labia minora - medial, thin hairless folds
– form vestibule contains urethral and vaginal openings
– form hoodlike prepuce over clitoris
• Clitoris - erectile, sensory organ
• Vestibular bulbs - erectile tissue around vagina
• Greater and lesser vestibular and paraurethral
glands open into vestibule for lubrication
28-17
Female Perineum Showing Vulva
28-18
Components of Female Perineum
28-19
Breasts
• Overlies pectoralis major
– conical body, nipple at apex
– axillary tail contains many lymphatic vessels
• Nipple surrounded by areola
– dermal blood vessels closer to surface
– melanocytes darken during pregnancy
– smooth muscle contracts wrinkling skin and erecting
nipple in response to cold, touch and arousal
• Suspensory ligaments from skin, muscle
• Nonlactating breast has little glandular tissue
28-20
Anatomy of Lactating Breast
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Anatomy of Lactating Breast
28-22
Sagittal Section of Breast
28-23
Breast Cancer
• 1 out of 8 American women
• Tumors begin with cells from mammary ducts
– may metastasize by lymphatics
• Symptoms may include palpable lump, skin
puckering, skin texture and drainage from nipple
• Most breast cancer is nonhereditary
– some stimulated by estrogen
• Risk factors include
– aging, ionizing radiation, carcinogenic chemicals,
alcohol, smoking and fat intake
– 70% lack risk factors
28-24
Cancer Screening and Treatment
28-25
Puberty
• Begins at age 9-10 (US)
• Triggered by rising levels of GnRH
– stimulates anterior lobe of pituitary to produce
• follicle-stimulating hormone (FSH)
• luteinizing hormone (LH)
• Follicles develop and begin to secrete
estrogen and progesterone
28-26
Puberty
• Thelarche - development of breasts
• Pubarche - growth of pubic and axillary hair;
apocrine and sebaceous glands
• Menarche - first menstrual period
– requires at least 17% body fat in teenager,
22% in adult
• leptin stimulates gonadotropin secretion
• improved nutrition ( body fat) has lowered avg.
age of onset to 12
• Female hormones secreted cyclically and
in sequence
28-27
Climacteric
• Midlife change in hormone secretion
– due to age related depletion of follicles
– occurs with menopause (cessation of
menstruation); average age of 52
• Results
– atrophy of uterus, vagina and breasts
– skin becomes thinner, bone mass declines,
and risks of cardiovascular disease
increase
– hot flashes (sudden dilation of cutaneous
arteries) occur several times a day
• HRT = hormone replacement therapy
28-28
Oogensis and Sexual Cycle
• Reproductive cycle - events occurring
between fertilization and birth
• Sexual cycle - events recurring every
month when pregnancy does not occur
– ovarian cycle = events in ovaries
– menstrual cycle = parallel changes in uterus
28-29
Oogenesis
• Monthly event produces haploid egg by meiosis
• Embryonic development of ovary
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female germ cells arise from yolk sac
differentiate into oogonia, multiply
transform into primary oocytes - early meiosis I
most degenerate (atresia) by childhood
by puberty 400,000 oocytes remain
• FSH stimulates completion of meiosis I,
produces secondary oocyte and 1st polar body
– proceeds to meiosis II and ceases until fertilization
– after fertilization , releases 2nd polar body
28-30
Oogenesis and Follicle Development
28-31
Sexual Cycle
• Averages 28 days, ranges from 20 to 45
• Hormone cycle: hierarchy of control
– hypothalamus pituitary  ovaries  uterus
• Follicular phase (2 weeks)
– menstruation occurs during first 3 to 5 days of cycle
– uterus replaces lost endometrium and follicles grow
• Luteal phase (2 weeks)
– corpus luteum stimulates endometrial thickening
– endometrium lost without pregnancy
28-32
Ovarian Cycle - Follicular Phase
• Menstruation (day 1) to ovulation(14) (variable)
• Difficult to predict date of ovulation
• Contains menstrual and preovulatory phases 28-33
Ovarian Cycle - Preantral Phase
• Discharge of menstrual fluid (days 1-5)
• Before follicle develops antrum
– primordial and primary follicles
28-34
Ovarian Cycle - Antral Phase
• Day 6 to 14, one dominant follicle advances to
mature (graafian) follicle; secretes estrogen
28-35
Ovarian Cycle - Ovulation
• Mature follicle ruptures, releases oocyte
influenced by LH
28-36
Histology of Ovarian Follicles
28-37
Pituitary-Ovarian Axis
28-38
Ovarian Cycle - Luteal Phase
• Corpus luteum - forms from ruptured follicle,
under influence of LH; secretes progesterone
28-39
Menstrual Cycle - Proliferative Phase
• Day 6-14 rebuild endometrial tissue
– mitosis occurs in stratum basalis
– result of estrogen from developing follicles
28-40
Menstrual Cycle - Secretory Phase
• Further thickening of endometrium due to
secretion and fluid accumulation -- not mitosis
• Due to progesterone stimulation of glands
28-41
Menstrual Cycle Premenstrual Phase
• Involution of corpus luteum, progesterone falls
– spiral arteries constrict causes endometrial ischemia
– stratum functionalis sloughs
28-42
Menstrual Cycle - Menstrual Phase
• Blood, serous fluid and endometrial tissue are
discharged
28-43
Female Sexual Response
28-44
Pregnancy and Childbirth
• Gestation (pregnancy)
– lasts an average of 266 days from conception
to childbirth
– gestational calendar measured from first day
of the woman’s last menstrual period (LMP)
• Birth predicted 280 days from LMP
– 3 three month intervals called trimesters
28-45
Prenatal Development
• Age based terminology
– blastocyst is less than 2 weeks old
– embryo is from 2 to 8 weeks old
– fetus is 9 weeks to birth
– neonate - newborn to 6 weeks
28-46
Hormones of Pregnancy
• HCG (human chorionic gonadotropin)
– secreted by trophoblast within 9 days of
conception
– prevents involution of corpus luteum
• Estrogens
– increases to 30 times normal before birth
– corpus luteum is source for first 12 weeks until
placenta takes over
– causes uterine, mammary duct and breast
enlargement
28-47
Hormones of Pregnancy
• Progesterone
– secreted by placenta and corpus luteum
– suppresses secretion of FSH and LH
preventing follicular development
– prevents menstruation, thickens endometrium
– stimulates development of acini in breast
• HCS (human chorionic somatomammotropin)
– secreted from placenta in direct proportion to
its size
–  mother’s glucose usage and  release of
fatty acids
28-48
Hormones of Pregnancy
• Aldosterone secretion rises
– fluid retention  mother’s blood volume
• Endocrine organs
– thyroid gland increases 50% in size
•  BMR of mother
– parathyroid glands enlarge
• stimulate osteoclasts to release additional calcium
from mother’s bones
28-49
Hormone Levels and Pregnancy
28-50
Adjustments to Pregnancy
28-51
Adjustments to Pregnancy
• Digestive System
– nausea
• first few months
– constipation and heartburn due to
•  intestinal motility
• pressure on stomach
• Metabolism
– BMR  may stimulate appetite
• healthy weight gain - 24 lb.
28-52
Adjustments to Pregnancy
• Nutrition
– placenta stores nutrients for 3rd trimester
• protein, iron, calcium, phosphates
– vitamin K
• reduces risk of hemorrhages in neonatal brain
– folic acid
• prevent neurological disorders
– spina bifida, anencephaly
• supplements must be started before pregnancy
28-53
Adjustments to Pregnancy
• Circulatory System
– mother’s blood volume and cardiac output rises 30%
• due to fluid retention and hemopoiesis
• by full term, placenta requires 625 mL of
blood/minute
– hemorrhoids and varicose veins
• from pressure on large pelvic blood vessels
28-54
Adjustments to Pregnancy
• Respiratory System
– minute ventilation  about 50%
• demands of fetus, higher maternal metabolic rate
• ventilation adjusted to keep PCO2 lower than normal
– respiratory rate 
• difficult to breathe deeply
28-55
Adjustments to Pregnancy
• Urinary System
– salt and water retention
• due to aldosterone and steroids
– GFR  by 50% and output is slightly elevated
• mother disposes additional metabolic wastes
–  frequency of urination
• due to bladder compression
28-56
Adjustments to Pregnancy
• Integumentary Systems
– stretch marks
• due to dermal stretching
– linea alba may become dark (linea nigra)
– temporary chloasma or “mask of pregnancy”
• blotchy darkening of skin over nose and cheeks
28-57
Childbirth - Uterine Contractility
• Parturition
– process of giving birth
• by contraction of uterine and abdominal muscles
• Braxton Hicks contractions
– throughout gestation
– strengthen late in pregnancy - false labor
28-58
Childbirth - Uterine Contractility
• Progesterone inhibits contractions
• Estrogen stimulates contractions
• Near full term - posterior pituitary releases
more oxytocin, uterus produces more
receptors
– directly stimulates myometrial contractions
– stimulates fetal membranes to produce
prostaglandins - synergists of oxytocin
• Stretching
– increases contractility of smooth muscle
– role in initiating labor
28-59
Labor Contractions
• Contractions begin 30 minutes apart and
eventually occur every 1-3 minutes
– periodically relax to  blood flow to placenta
and fetus
– contractions strongest in fundus and body of
uterus, pushes fetus into cervix
28-60
Labor Contractions
• Self-amplifying cycle of stretch and
contraction
– positive feedback cycles increase contractions
• cervical stretching  oxytocin secretion 
uterine contraction  repeat
• reflex arc from uterus  spinal cord 
abdominal skeletal muscles
28-61
Pain of Labor
• Ischemia of myometrium
• Stretching of cervix, vagina and perineum
– episiotomy prevents tearing
• Large fetal head in a narrow pelvic outlet
28-62
Stages of Labor -- Early Dilation
• Widening of cervical canal by effacement (thinning) of
cervix to reach 10 cm -- diameter of fetal head
• Rupture of fetal membranes and loss of amniotic fluid
28-63
Stages of Labor -- Late Dilation
Dilation reaches 10 cm in 24 hours or less in primipara
(first baby) and in as little as few minutes in multipara
28-64
Stages of Labor -- Expulsion
• Time baby’s head enters vagina until delivery
– up to 30 minutes
• Valsalva maneuver helps to expel fetus
28-65
Stages of Labor -- Placental
• Uterine contractions continue causing placental
separation
28-66
Crowning (Expulsion Stage)
28-67
Expulsion Stage (cont.)
28-68
Placental Stage
28-69
Puerperium
• First 6 weeks after delivery
• Anatomy and physiology return to normal
– involution of uterus
• to pre-gravid weight in 4 weeks
• accomplished by autolysis by lysosomal enzymes
– vaginal discharge called lochia
– breastfeeding promotes involution
• suppresses estrogen secretion
• stimulates oxytocin which causes myometrial
contraction
28-70
Mammary Gland Development
• Lactation
– synthesis and ejection of milk from mammary
glands in breast
• Ducts grow and branch
– due to high estrogen levels in pregnancy
• Followed by budding and development of
acini at the ends of the ducts
– due to progesterone
28-71
Colostrum and Milk Synthesis
• Colostrum forms in late pregnancy
– similar to breast milk; contains 1/3 less fat,
thinner
– first 1 to 3 days after birth
– contains IgA protection from gastroenteritis
• Synthesis is promoted by prolactin (from
pituitary)
– synthesis of hormone begins 5 weeks into
pregnancy, by full term it is 20x normal level
– steroid hormones from placenta oppose it until
birth
28-72
Colostrum and Milk Synthesis
• At birth, prolactin secretion drops, but 
20 times after nursing
– without nursing, milk production stops in 1
week
• 5-10% of women become pregnant while
nursing
– inhibition of GnRH and reduced ovarian
cycling
28-73
Prolactin and Lactation
28-74
Milk Ejection
• Controlled by a neuroendocrine reflex
– infant’s suckling stimulates sensory
receptors in nipple, signaling hypothalamus
and posterior pituitary to release oxytocin
– oxytocin stimulates myoepithelial cells
• Myoepithelial cells surround secretory
cells in acinus
– contract to squeeze milk into duct
• milk flow within 30-60 seconds after suckling
begins
28-75
Breast Milk
• Supplies antibodies and colonizes
intestine with beneficial bacteria
• Colostrum and milk have a laxative effect
that clears intestine of meconium (green,
bile-filled fecal material in newborn)
• Nursing woman can produce 1.5L per day
• Cow’s milk not a good substitute
– 1/3 less lactose but 3 times as much protein
– harder to digest and more nitrogenous waste
(diaper rash)
28-76
Contraceptive Devices
28-77