Reproductive System
Objectives:
1. 12.0 Identify structures and functions
of the reproductive system
2. 12.1 Differentiating between male and
female reproductive systems
3. 12.3 Identifying disorders of the
reproductive system
Examples: endometriosis, sexually
transmitted diseases, prostate cancer
Preassessment Quiz
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9.
What is a male sex cell called?
What is the male primary sex organ?
What do the primary sex organs do?
Name 2 internal male accessory organs.
Name 2 external male accessory organs.
What is a female sex cell called?
What is the female primary sex organ?
Name 2 internal female accessory organs.
Name 2 external female accessory organs.
Organs of the Male Reproductive
System
• Label and color Figure 19.1
1. Testes
• Enclosed in a tough, white, fibrous
capsule (tunica albuginea) within
the scrotum (2.)
• Connective tissue thickens along
inferior border of capsule and
projects into testis, dividing it into
250 lobules
• Each lobule contains 1-4 highly
convoluted seminiferous tubules.
Testes, continued…..
• Seminiferous tubules join in a
complex network called the rete
testis.
• Ducts branching off the rete testis
join a single, convoluted tube
called the epididymis (3.)
• Once the epididymis straightens, it
becomes the vas deferens (4.)
Structure of the Testes,
continued…..
• What does spermatogenic mean?
• Inside the seminiferous tubules:
– Spermatogenic cells (specialized
epithelial cells) line the walls.
– They form sperm cells that collect in
the lumen of the tubule.
• Between the tubules are interstitial
cells (“cells of Leydig”), which
produce male sex hormones.
Testicular Cancer
• Arises from the epithelial cells of
the seminiferous tubules. (What are
the names of these cells?)
• Signs:
– Painless swelling of the testis
– Scrotal mass attached to the testis
• Treatments:
– Surgical removal of testis
– Radiation and/or chemotherapy
Formation of Sperm Cells
• Where are they formed???
• Males produce sperm cells
continually throughout their
reproductive lives.
• They collect in the lumen and pass
to the epididymis, where they
mature and accumulate.
Formation of Sperm Cells,
continued…..
• 3 main parts:
1.Head
a. Mainly a nucleus containing 23
chromosomes
b. Acrosome – a projection at the end of
the head that contains enzymes to
assist in penetrating an egg
2.Midpiece - contains many mitochondria
3.Tail - flagella; function????
Spermatogenesis
• Mitosis vs. meisosis
Spermatogenesis, continued…..
Male Internal Accessory Organs
1. Epididymis
2. Vas deferens
3. Seminal vesicle
4. Prostate gland
5. Bulbourethral glands
6. Semen (*)
3. Epididymis
• Convoluted tube that is connected
to ducts within the testis, emerges
from the top of the testis, descends
along the posterior surface of the
testis, and ascends to become the
vas deferens.
• Immature, nonmotile sperm mature
as they are moved through the
epididymis.
4. Vas deferens
• Travels from epididymis to just
behind the bladder
• Unites with the duct of a seminal
vesicle (5) to form an ejaculatory duct
(6)
• Ejaculatory duct passes through the
prostate gland (7) and empties into
the urethra (8)
5. Seminal vesicle
• Convoluted sac-like structure
attached to the vas deferens near the
base of the urinary bladder
• Secretes:
– a slightly alkaline fluid to regulate pH
of tubular contents
– fructose to provide energy to sperm
cells
– prostaglandins to stimulate muscular
contractions in female reproductive
organs to help move sperm cells
7. Prostate Gland
• Chestnut-shaped structure that
surrounds proximal portion of
urethra
• Ducts open into urethra
• Secretes thin, milky, alkaline fluid
– Neutralizes acidic fluid containing
sperm cells
– Neutralizes acidic vaginal secretions
– Enhances motility of sperm cells
10. Bulbourethral Glands
• AKA, Cowper’s glands
• Located inferiorly to the prostate
gland, within muscle fibers of
external urethral sphincter
• Secretes mucuslike fluid to lubricate
the end of the penis for sexual
intercourse
• (As always, females do most of the
work of producing lubricating fluid. :)
Semen
• The fluid the male urethra releases
during ejaculation
• Consists of:
– Sperm cells
– Secretions of the seminal vesicles,
prostate gland, and bulbourethral
glands
• About 120 million sperm cells/mL
semen
• 2-5 mL semen released at a time
Enlarged Prostate Gland
• Where is the prostate gland
located???
• So, what would happen if the
prostate gland became enlarged?
• Testing for prostate cancer:
– Rectal exam
– PSA (prostate-specific antigen) blood
test to check for a cell surface protein
found on prostate cells
– Ultrasound
Treatment Options for Enlarged
Prostate Gland
• Surgical removal of prostate
• Radiation
• Microwave energy delivered
through a probe inserted into the
urethra or rectum
• Freeze tumor with liquid nitrogen
delivered by a probe through the
skin
• Others
Male External Accessory Organs
1. Scrotum
2. Penis
2. Scrotum
• 1.Pouch of skin that houses the
testes
• 2. Medial septum divides it into 2
chambers
• 3. Protects and aids in temperature
regulation of the testes
11. Penis
• Conveys urine and semen through
the urethra to the outside
• The body (shaft) has 3 columns of
erectile tissue:
1. A pair of dorsally located corpora
cavernosa (12)
2. A single, ventral corpus
spongiosum (13)
11. Penis, continued…..
• Corpus spongiosum:
– Urethra passes through it
– Enlarges at distal end to form the glans
penis (14)
• Glans penis
– Covers the ends of the corpora cavernosa
– Bears urethral opening (orifice)
– Contains sensory receptors
• Prepuce (15) – fold of skin that covers the
glans penis; removed in circumcision
Erection, Orgasm, and Ejaculation
• Sexual stimulation leads to
parasympathetic nerve impulses
from the spinal cord to release NO, a
vasodilator.
• Arteries leading to the penis dilate.
• Pressure from arterial blood filling
the vascular spaces of erectile tissue
compress the penis veins.
• Venous blood cannot flow out of the
penis, erectile tissue fills, and an
erection is produced.
Erection, Orgasm, and Ejaculation,
continued…..
• Emission and ejaculation
accompany male orgasm.
• Emission: the movement of sperm
cells from the testes and secretions
from the prostate gland and seminal
vesicles into the urethra.
• Ejaculation: the process of forcing
semen through the urethra to the
outside
Erection, Orgasm, and Ejaculation,
continued…..
• Emission and ejaculation events
occur so that:
1.Fluid from bulbourethral glands is
expelled first
2.Fluid from the prostate gland is
released next
3.Then sperm cells
4.Lastly, fluid from the seminal
vesicles
Erection, Orgasm, and Ejaculation,
continued…..
• Following ejaculation:
• Arteries that supply erectile tissue
contract,
• Veins of the penis “drain” the
spaces of the erectile tissue,
• Penis returns to flaccid state
Hormonal Control of Male
Reproductive Functions
• Hormones are secreted by:
– Hypothalamus
– Anterior pituitary gland
– Testes
• Functions:
– Development of sperm cells
– Development of secondary sex
characteristics
Hypothalamic and Pituitary
Hormones
• Hypothalamus secretes
gonadotropin-releasing hormone
(GnRH) to anterior pituitary gland
• In response, anterior pituitary gland
secretes gonadotropins:
1. Luteinizing hormone (LH)
2. Follicle-stimulating hormone (FSH),
aka interstitial cell-stimulating
hormone (ICSH)
Hypothalamic and Pituitary
Hormones, continued…..
• FSH (ICSH) promotes development of
___________.
• Testicular interstitial cells secrete
male sex hormones.
• LH stimulates supporting cells of
seminiferous tubules to respond to
testosterone.
Hypothalamic and Pituitary
Hormones, continued…..
• FSH + testosterone + supporting
cells stimulate spermatogenic cells
to give rise to ______________.
• Supporting cells secrete inhibin, a
hormone which inhibits the anterior
pituitary gland, preventing secretion
of FSH.
Male Sex Hormones
• Called “Androgens” (???)
• Where are they produced?
• Most in testicular interstitial cells,
but small amounts in adrenal cortex
• What is the main male sex
hormone?
• Testosterone production begins
before birth, continues a few weeks
after, and then ceases until puberty.
Actions of Testosterone
• Stimulates enlargement of testes and
male accessory organs
• Stimulates development of male
secondary sex characteristics:
1. Increased growth of body hair
2. Enlargement of the larynx and
thickening of the vocal cords
3. Thickening of the skin
4. Muscle growth, widening of shoulders,
narrowing of waist
5. Thickening and strengthening of bones
Actions of Testosterone,
continued…..
• Increases rate of cellular
metabolism
• Increases rate of RBC production
Regulation of Male Sex Hormones
• More testosterone = more developed
secondary sex characteristics
• Increased levels of testosterone
inhibit the hypothalamus.
• What effects would inhibition of the
hypothalamus have?
Organs of the Female
Reproductive System
• Label Figure 19.7
1. Ovaries
• Ovarian tissues are subdivided:
– Inner medulla
– Outer ______
• Ovarian cortex appears granular
due to tiny masses of cells called
ovarian follicles (19).
Ovaries, continued…..
• Primordial(???) follicles:
– Form before birth
– Found in outer region of cortex
– Each contains a SINGLE primary
oocyte, surrounded by follicular cells
(specialized epithelial cells)
– No new primary follicles are formed
during life.
– Millions of oocytes at birth; 400,00 at
puberty; 400-500 released during
reproductive years
Oogenesis:
• The process of egg cell formation
Follicular Maturation
Ovulation
• The process of releasing a
secondary oocyte (18) and its
associated polar body from the
ovary
Female Internal Accessory Organs
1. Uterine tubes
2. Uterus
3. Vagina
2. Uterine Tubes
• Opens near the ovaries and travels
medially into the uterus
• Infundibulum (16): the funnelshaped end of the uterine tube at the
ovary
• Fimbriae (3): finger-like projections
at the end of the infundibulum
Uterine Tubes, continued…..
• Oocytes are moved into and along
the tubes by:
– Ciliated epithelial cells
– Peristaltic contractions
• Fertilization occurs in the uterine
tubes, and the oocyte becomes an
egg (ovum)
4. Uterus
• Hollow, muscular, pear-shaped
organ
• Located medially in the anterior
portion of the pelvic cavity
• Body of the uterus (22): upper 2/3
• Cervix (5):
– lower 1/3
– Connects to vagina (6)
• Cervical orifice (24): opening from
uterus to vagina
Uterine Wall
1. Endometrium(20)– mucosal layer
2. Myometrium(21) - _______ layer
3. Perimetrium(23) – serosal (thin,
watery-filled) layer
6. Vagina
• Fibromuscular tube that extends
from the uterus to the outside of the
body
• Located posterior to urinary bladder
(11) and urethra (12), and anterior to
rectum (14) (see Fig. 19.7 diagram)
• Functions:
1. Conveys uterine secretions
2. Receives penis during intercourse
3. Channel for birth
Vaginal Wall
1. Inner mucosal layer
• LACKS mucosal glands
• Mucous comes from uterine glands
and vestibular glands at mouth of
vagina
2. Middle muscular layer
• Mostly smooth muscle (involuntary)
• Bulbospongiosus muscle (voluntary)
closes off vaginal orifice (7)
Vaginal Wall, continued…..
3. Outer fibrous layer
– Dense connective tissue
– Attaches vagina to surrounding
organs
• Urethra (13)
• Rectum (14)
Female External Accessory
Organs
1.
2.
3.
4.
Labia majora
Labia minora
Clitoris
Vestibule
9. Labia Majora
• Enclose and protect other external
accessory organs
• Correspond to male scrotum
• Composed of 2 rounded folds of
adipose tissue, smooth muscle, and
skin that lie on either side of the
other accessory organs
• Anterior ends join to form the mons
pubis
8. Labia Minora
• 2 flattened folds that lie between the
labia majora
• Join with the labia majora
posteriorly
• Merge anteriorly to form a
protective, hoodlike covering
around the clitoris
10. Clitoris
• Small projection at the anterior end
of the vulva (the external accessory
organs that surround the vaginal
opening)
• Corresponds to male penis:
– 2 columns of erectile tissue (corpora
cavernosa)
– Glans, erectile tissue at anterior end,
contains sensory nerve endings
• So what would be its function?
Vestibule
• The space enclosed between the
labia minora
• Vestibular glands:
– 2 at the opening of the vagina
– Correspond to male bulbourethral
glands (FUNCTION?)
• Vestibular bulbs:
– lie beneath the mucosa of the
vestibule on either side
– A mass of erectile tissue
Erection , Lubrication, and Orgasm
• Where is erectile tissue located?
• Once these tissues are stimulated,
parasympathetic nerve impulses
release nitric oxide (a vasodilator).
• What effect would a vasodilator
have?
• If stimulation is sufficient,
vestibular glands secrete mucus
into the vagina. (WHY??)
Erection , Lubrication, and
Orgasm, continued…..
• The muscles of the perineum (area
b/t the anus and external accessory
organs) and walls of the uterus and
uterine tubes contract rhythmically.
• Why would all these areas need to
contract?
• Contractions help transport sperm
to the upper ends of the uterine
tubes.
Hormonal Control of Female
Reproduction Functions
• Hormones are secreted by:
– Hypothalamus
– Anterior pituitary gland
– Ovaries
• Functions:
– Control development and maintenance
of female secondary sex characteristics
– Maturation of female sex cells
– Changes during monthly reproductive
cycle
Female Sex Hormones
• About age 10, hypothalamus begins
secreting GnRH, which stimulates
_____________ to release _______
and _______.
• Female sex hormones belong to 2
basic groups:
– Estrogens (estradiol, estrone, and
estriol)
– Progesterone
Estrogens
• Produced primarily in the ovaries
• Stimulate enlargement of ALL
accessory organs
• Develop secondary sex
characteristics:
– Development of breasts and ductile
system of mammary glands
– Increased deposits of adipose tissue
subcutaneously and in breasts, thighs,
and buttocks
– Increased vascularization of the skin
Progesterone
• Also produced primarily in the
ovaries
• Promotes changes in the uterus
during reproductive cycle
• Affects mammary glands
• Helps regulate secretion of
gonadotropins from _________
gland
Female Reproductive Cycle
• AKA, menstrual cycle
• Regular, recurring changes in the
uterine lining
• Ovarian cycle: changes in the
ovaries (occurs along with
menstrual cycle)
• Menarche: female’s first menstrual
cycle
Female Reproductive Cycle,
continued…..
• Hypothalamus secretes
____________, which stimulates the
_________ to secrete _______ and
______.
• FSH stimulates maturation of an
ovarian follicle.
• LH stimulates ovarian cells to
produce testosterone, which is
used to produce estrogens.
Female Reproductive Cycle,
continued…..
• Follicular cells produce estrogens:
– Maintain secondary sex
characteristics
– Cause uterine lining to thicken
• While follicle matures (1st 14 days of
cycle), the estrogens secreted
INHIBIT release of LH by the
anterior pituitary gland.
• Once follicle is mature, LH is
released.
Female Reproductive Cycle,
continued…..
• The released store of LH weakens
and ruptures the bulging follicular
wall, releasing the oocyte from the
ovary. (What is this step called?)
• The “empty follicle” fills with blood,
clots, and forms a temporary
glandular structure called the
“corpus luteum”.
• Corpus luteum secretes
progesterone and estrogens.
Female Reproductive Cycle,
continued…..
• Corpus luteum secretes progesterone
and estrogens:
– Progesterone causes the endometrium
to become more vascular and glandular.
– Estrogens and progesterones inhibit
release of LH and FSH from _______, so
no new follicles develop while corpus
luteum is active.
Female Reproductive Cycle,
continued…..
• If egg is unfertilized, corpus luteum
begins to degenerate on about day
24 of cycle, becoming a “corpus
albicans”
• What would happen to estrogen and
progesterone levels when the
corpus luteum “dies”?
• What do you think is the main
source of estrogen and
progesterone in a pregnant female?
Female Reproductive Cycle,
continued…..
• In response to decreased levels of
estrogen and progesterone, blood
vessels in the endometrium constrict:
– No more nutrients and oxygen to
thickened uterine lining
– Tissues die and slough off
– Blood escapes from damaged
capillaries
Female Reproductive Cycle,
continued…..
• Because estrogen and
progesterone levels are low, the
hypothalamus and anterior pituitary
glands are no longer inhibited, and
cycle starts anew.
Female Reproductive Cycle,
continued…..
• Figure 19.13, p.514
Menopause
• The end of monthly cycles
• Caused by aging of ovaries which,
after about 35 years of cycling,
contain too few primary follicles to
have one mature each month.
• Thus, no ovulation occurs, and
blood levels of estrogen and
progesterone plummet, causing
changes in secondary sex
characteristics.
Mammary glands
• Accessory organs specialized to
secrete milk following pregnancy
• Contained within the breasts
• Mammary glands are composed of 1520 lobes, which contain alveolar glands
that lead to an alveolar duct, which
leads to a lactiferous duct, which leads
to a nipple and opens to the outside.
• Males have mammary glands which do
not develop at puberty. (They lack
ovarian hormones.)
Critical Thinking
1. Why must the chromosome
number be halved in sperm cells
and oocytes?
2. Sometimes a sperm cell fertilizes a
polar body rather than an oocyte.
An embryo does not develop, and
the fertilized polar body
degenerates. Why is a polar body
unable to support development of
an embryo?
Critical Thinking, continued…..
3. Some men are unable to become
fathers because their spermatids
do not mature into sperm. Injection
of their spermatids into their
partner’s secondary oocytes
sometimes results in conception. A
few men have fathered healthy
babies this way. Why would this
procedure work with spermatids,
but not with primary
spermatocytes?
• What is the largest cell in the human
body?
• What is the smallest cell?