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Sexual reproduction: each parent contributes
half of genetic material for each offspring
 Advantage of offspring being genetically different
 Requires gametes, cells for reproduction that
contain half as many chromosomes as a normal
cell
 Fertilization is formation of one cell containing
genetic material from two gametes
 Zygote is the fertilized cell that’s produced by
combining both gametes
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Asexual reproduction: one parent produces
an offspring that’s a clone (same genetic
information)
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Males and females have primary
reproductive organs known as gonads,
the site in which gametes are made
 Males—testes, or testicles
 Females—ovaries
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Gametes are the sex cells
 Males—sperm
 Females—oocytes, or eggs
Male and female reproductive systems do not become
functional until later in life
 As embryos, the sexes are indistinguishable until the
7th-8th week of development
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 SRY gene in the Y chromosome allows the male sex organs
to develop, starting with the testes
 Lack of the SRY gene for females will cause ovaries to
develop
 Body’s “default plan” is to develop female reproductive
anatomy
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At birth, FSH (follicle-stimulating hormone) and LH
(luteinizing hormone) levels are high but decline and
remain low for 8 to 14 years until the onset of puberty
 Because of this, the testes do not produce testosterone and
the ovaries do not produce estrogen or progesterone for that
time
Puberty is the final maturation of the reproductive
system, when sexual reproduction becomes
possible
 Between 8-13 in females, 9-14 in males
 Initial stimulus is elevated secretion of
gonadotropin-releasing hormone (GnRH) released
by the hypothalamus
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 GnRH causes the pituitary to produce FSH and LH
which stimulates maturation of reproductive organs and
cause appearance of secondary sex characteristics
First phase of puberty is breast growth, followed
by the development of secondary sex
characteristics: growth of axillary (underarm) and
pubic hair, gradual changes in the width of the
pelvis and size of pelvic outlet to facilitate
pregnancy and childbirth, skeletal growth
accelerates
 About two years after the beginning of puberty,
menarche—the first menstrual bleeding—occurs
 Ovulation cycles typically are irregular for the first
one or two years and become more regular as
puberty reaches its conclusion
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First visible phase of puberty is growth of
scrotum and testes, followed by secondary
sex characteristics: pubic and axillary hair
growth, increase in larynx and length of vocal
folds causes the voice to deepen, penis
grows larger in proportion to body size
During early years of puberty, males typically
experience erections at unexpected times, as
well as emission of semen during sleep
By end of puberty, mature sperm are present
in semen
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Scrotum is pouch of skin that hangs outside body
below pelvic cavity, in midline and anterior to anus
 Contains two testes and associated ducts
 Testes temperature is cooler than core body temp. and
sperm formation is most vigorous at this cooler temp.
 When scrotum is cold, muscles contract to pull organ
closer to body…when scrotum is warm, muscles relax to
allow scrotum more freedom and greater surface area
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Testes are held in place by the epididymis
 Contain a dense network of small tubes were sperm
form called seminiferous tubules which connect to
epididymis…as tube runs upwards, it is known as
ductus deferens (vas deferens)
Designed to deliver sperm to female reproductive
tract
 Shaft of penis leads to glans penis, the enlarged
end
 Prepuce, or foreskin, is loose fold of skin that
covers much of glans penis
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 Circumcision is surgical removal of prepuce and has
been shown to reduce risk of certain sexually
transmitted diseases
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Shaft of penis contains erectile tissue and urethra
 Opening at outer end of urethra is external urethral
orifice
 Erectile tissue in shaft contains spaces in which blood
can pool allowing penis to become enlarged and rigid
during sexual arousal due to engorgement with blood
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Male duct system transports sperm from
the testes, where its formed, to the
external urethral orifice at the tip of the
penis
Sperm from seminiferous tubules of each
testis epididymis ductus deferens
(scrotum into pelvic cavity in body) + duct
from seminal gland  ejaculatory duct
prostate urethra  out of body during
sexual intercourse
Semen is fluid that contains sperm (10% of
volume of semen) and most seminal volume
comes from accessory glands
 Two seminal glands produce 70% of volume of
semen
 The prostate gland sits directly under the bladder
and it secretes fluid that makes up seminal volume
 Two bulbourethral glands that lie below the
prostate contribute a small amount of fluid to
semen
 During ejaculation, the total volume of semen
ejected typically is 2-5 mL and contains 20-150
million sperm cells per mL
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Male sexual response has two complementary
components: erection and ejaculation
 Erection permits penis to gain entry into female
reproductive tract
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 Neural impulses travel along parasympathetic nerve fibers to
erectile tissue of penis triggering release of nitric oxide which
in turn causes more blood to fill tissue and penis becomes
erect
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Ejaculation is discharge of sperm from ejaculatory duct
 Sympathetic nerve impulses causes peristaltic contractions
of smooth muscle in male duct system and male accessory
glands AND contraction of urethral sphincter at base of
bladder preventing mix of semen and urine
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The two oval shaped ovaries are positioned
against the posterior wall of the pelvic cavity,
have a fibrous outer covering, but do NOT
contain ducts but ovarian follicles instead
Each follicle inside the ovaries contains a
single oocyte and multiple surrounding cells
At any given time, the ovaries contain
follicles in different stages of maturation
Each month one follicle reaches maturity,
and the oocyte that it contains is released
from its ovary during ovulation
Each of the two uterine tubes begins at the
lateral end of its ovary and curves up and
around the ovary to terminate at the top
lateral portion of the uterus
 Hollow tube is open at the ovary
 Has fringe-like projections called fimbriae
which wrap part of the way around the ovary
 At time of ovulation, vibrating cilia of fimbriae
sweep fluid and ovulated oocyte into uterine
tube towards the uterus
 Uterine tube passes through wall of uterus
and opens into lumen, or cavity, of uterus
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Aka womb, a hollow muscular organ located in
front of the rectum and behind the bladder
Purpose is to receive and nourish a fertilized
egg, and to expel the fetus by forceful muscular
contractions during childbirth
Three layers: perimetrium, myometrium, and
endometrium (shed during menstruation)
Narrow, lower end of uterus called cervix
(connects lumen of uterus to lumen of vagina)
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Thin-walled tubular structure below uterus
Sometimes called birth canal because
infant passes through vagina during birth
During intercourse, sperm delivered to
lumen of vagina
pH of vagina is acidic to prevent bacterial
infections
Apart from childbirth or intercourse, walls
of vagina touch each other
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Reproductive structures on the outside of the body aka
vulva
Includes: labia, mons pubis, clitoris, and vestibule
Mons pubis (pubic mound) is region of skin and underlying
fat in front of vaginal opening on which pubic hair grows
Labia majora are two skin folds that lie parallel on either
side of vaginal opening
Inside labia majora are the labia minora, a smaller pair of
skin folds
Within labia minora is the vestibule, the recessed area in
which the vaginal and urethral openings lie
The clitoris, a small structure at the anterior end of the
vestibule, is composed of erectile tissue and covered
anteriorly by a skinfold called the prepuce and an exposed
tip is called the glans…richly endowed with sensory nerve
endings
Produce milk for the newborn baby
Increased estrogen in females during puberty
stimulates maturation of mammary glands and is
capable of lactation but does not produce milk until
the hormone prolactin is released (after childbirth)
 Modified sweat glands…part of the skin that lie on
top of pectoralis major
 Contain 15 to 20 lobes internally, each of which
has many smaller lobules and each lobe secretes
its milk into a lactiferous duct that opens at the
nipple
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“Monthly” cycle of female reproductive system
Generally spans 28 days on average but actual
duration of cycle varies from about 21 to 40
days
Changes occur in ovarian cycle and uterine
cycle, but these changes occur at the same
time
Two main phases: follicular phase (days 1-14) and luteal
phase
 Ovulation, the release of an oocyte, marks the end of
the follicular phase and beginning of luteal phase
 Changes in ovary during ovarian cycle:
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1. Primary follicles
2. Secondary follicle
3. Late secondary follicle
4. Vesicular follicle
5. Ovulation--The secondary oocyte is released, along with
surrounding corona radiata cells
6. Remaining cells of the follicle turn into the corpus luteum.
7. If fertilization does not occur, the corpus luteum turns into a
small bundle of scar tissue.
Three phases: menstrual phase, proliferative phase,
and secretory phase
 Menstrual phase: days 1 to 4/5 when outer layer of
endometrium breaks down producing menstrual
discharge
 Proliferative phase: begins as soon as menstrual phase
is complete and functional layer of endometrium grows
back due to rising levels of estrogen
 Secretory phase: during ovulation, rapid regrowth of
endometrium slows due to rising levels of progesterone
and also develops dense network of blood vessels and
nutrient-secreting glands that will nourish an embryo, if
one implants
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Sexual stimulation activates parasympathetic
nerves to erectile tissue of clitoris which
becomes engorged with blood
Autonomic nerves activate smooth muscle
fibers in nipple causing it to become erect
Increases in both vestibular gland and vaginal
wall secretions stimulate production of
lubricating fluid that facilitates intercourse
In females, orgasm is not required for
conception
Sperm must travel from vagina to cervical canal,
through the cervical canal to the uterus, through the
uterus to the uterine tube, and then along the uterine
tube to the oocyte
 Capacitation, the process by which sperm becomes
able to penetrate and fertilize an oocyte, takes as much
as 10 hours
 When the sperm finds the oocyte, they wiggle past the
cells of the corona radiata to the zona pellicuda where
the acrosomal enzymes of hundreds of sperm drill a
hole so the sperm’s chromosomes enter the cytoplasm
of the oocyte
 Net effect of sodium entry, calcium release, and
chemical reaction with water outside of oocyte prevent
additional sperm from fertilizing the oocyte
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Aka gestation, the period from fertilization to birth
Lasts approximately 265 days (280 days or 40 weeks if
measured from first day of last menstrual cycle)
After zygote has formed, it continues its slow movement
toward the uterus
3 days after fertilization, the zygote is a solid ball of 16
cells called morula
By day 4, a blastocyst develops
Around day 15 of the uterine cycle, implantation of the
blastocyst to the uterine wall occurs
Human chorionic gonatropin (hCG) is present in
pregnant women and protects the trophoblast which is
why it is used in pregnancy-test kits.
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When embryo is tiny, can get nutrients by simple
diffusion from tissues of endometrium. As it grows, it
needs more nutrients than endometrium can supply
Placenta is organ that grows in uterus to meet nutritional
needs of embryo and contains intertwining blood
vessels from cardiovascular systems of fetus (8 weeks
of development) and mother
Cardiovascular system is first to function—3 ½ weeks
after fertilization immature heart begins to pump blood
Fetus surrounded by set of membranes (amnion,
chorion, decidua capsularis) and bathed in clear
amniotic fluid
Umbilical cord contains two arteries and one vein,
connects the fetus to placenta
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Aka parturition, normally occurs between
38 to 42 weeks after the first day of the
last menstrual period
High levels of estrogen and progesterone
cause uterine muscle cells to become
sensitive to oxytocin which causes uterine
muscle contractions
Example of positive feedback
Three stages: dilation, expulsion, and
delivery of placenta
 Vertex presentation, or head down position
most common
 Dilation stage begins with uterine
contractions and ends with a full widening
(10 cm) of the cervical canal and is usually
the longest part of labor
 Expulsion is the period from full dilation to
delivery of the baby and lasts less than an
hour in most cases
 Delivery of the placenta is the last stage of
birth
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Production of milk by mother
Breast milk is uniquely important source of
nutrition for developing infant because it contains
amino acids, fats, carbohydrates, vitamins and
ANTIBODIES that are well absorbed by the
infant’s digestive system
Prolactin stimulates the secretory cells of
mammary glands to produce milk while oxytocin
causes the let-down reflex—the contraction of
smooth muscle cells in mammary glands which
allows milk to be squeezed toward and out of the
nipple
Abstinence: refraining from sexual
intercourse…absolutely most effective
 Various reasons for avoiding pregnancy: religious,
ethical, personal concerns
 Methods of contraception
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Sterilization
Hormones
IUD
Diaphragm
Condom
Withdrawal
Rhythm
Menopause
Decrease in estrogen and progesterone
production
 Narrowing of vaginal opening, loss of tissue
elasticity, and a decrease in vaginal
secretions
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Sexual response is slower
Obtaining and maintaining an erection
becomes more difficult
Prostate gland size increases, testes
decrease in size, and sperm level
decreases
Testosterone level decreases
Viscosity of seminal fluid diminishes
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In males: insufficient healthy-sperm count or
inability of sperm to be released
In females: failure to ovulate, inability of egg to
reach uterine tube and travel to uterus, inability of
blastocyst to implant successfully on endometrium
Treatment: lifestyle changes (less alcohol, drugs,
tobacco use, and stress), drugs to induce
ovulation, surgery to correct anatomical issues
Assisted reproductive technologies are available,
most common being in vitro fertilization (IVF)
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Acquired immune deficiency syndrome is
the most lethal sexually transmitted
disease caused by the human
immunodeficiency virus
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In the US, rates have been falling for the past
35 years but is still a common infectious
disease among teenagers and young adults
May cause pain during urination, unusual
discharge of fluid from the vagina or penis, or
no symptoms at all.
Can lead to infertility in women even if no
symptoms are produced
Can be successfully treated with antibiotics
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Most commonly reported STD in US
Incidence has been rising
Often causes no symptoms, but can damage
female reproductive tract leading to infertility
and ectopic pregnancy
Should be screened annually if sexually active
woman
Can be successfully treated with antibiotics
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Caused by herpes simplex virus type 1 or 2
HSV-2 infects about one out of six Americans
between 14 and 49 years of age
May cause blisters or sores in the genital or
anal area or near the mouth, or it may cause no
symptoms
Most people are unaware they have it
No cure, but is manageable with antiviral drugs
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Causes genital warts and cervical cancer, but
may produce no symptoms
Most common STD in the US
Affects both men and women
6 million infections emerge each year
½ of all sexually active adults will be infected
with HPV at some point in life
In most people, the immune system eliminates
HPV, but it takes about 2 years to do so
Inflammation of the uterus, uterine tubes, ovaries,
and other organs of abdominopelvic cavity
 PID is caused by bacterial infection and a
potentially serious complication of chlamydia and
gonorrhea in females
 Mild to severe pelvic pain, fever, and painful
urination
 Most symptoms go unrecognized
 Treated with antibiotics
 Can cause permanent damage to reproductive
organs and infertility
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2nd highest incidence of cancer among men,
and 2nd most frequent cause of cancer mortality
among men
Slow-growing, and originate in the gland cells
that produce the fluid added to semen
PSA (prostate-specific antigen) tests are used
to screen for prostate cancer
Treatment includes surgery to remove cancer
cells, radiation therapy, and chemotherapy
These affect about 70,000 American women
annually and cause more than 20,000 deaths
each year
 Cancer of uterus is most frequently diagnosed
cancer of female reproductive tract through
abnormal uterine bleeding and requires removal
of entire uterus, uterine tubes, and ovaries
(hysterectomy)
 Cancer of ovary is 5th most common cause of
cancer-related death among women since it does
not cause symptoms until the disease has spread
 Cervical cancer is 3rd most commonly diagnosed,
and 3rd as cause of death among US women. Pap
smears have significantly reduced cervical cancer
mortality over the last 35 years
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Type of cancer that forms in the tissues of the breast—
usually in the ducts and lobules
Can affect both men and women
More women die from breast cancer than from any other
cancer
Factors that raise a woman’s risk: advanced age, family
history, menarche at an early age, late onset of
menopause, being overweight, never having given birth
Yearly mammogram recommended for women over 40
Breast self-exam performed by a woman each month
aids in early detection and successful treatment
Treatment ranges from lumpectomy (small region of
cancer tissue removed) to radical mastectomy (all
breast tissue and surrounding lymph nodes are
removed)