THE MALE
REPRODUCTIVE SYSTEM
HOMEOSTASIS
 male & female reproductive organs work together to
produce offspring
 female reproductive organs also contribute to
sustaining the growth of embryos and fetuses
Sexual Reproduction
 process by which organisms produce offspring by
making germ cells (gametes)
 fertilization: when male gamete (sperm) unites with
female gamete (secondary oocyte)  fertilized egg
 males & females have anatomically distinct
reproductive organs that function to
1. produce gametes
2. facilitate fertilization
3. sustain growth of embryo & fetus (female)
Reproductive Organs
Females
Males
 Gonads: testes
 Gonads: ovaries
 Ducts
 Ducts

store & transport
gametes
 Accessory Sex Glands
 Supporting Structures

Penis

transport gametes
 Accessory Sex Glands
 Supporting Structures:

Uterus
Male Reproductive System
 Organs:
Testes
2. system of ducts
3. accessory sex glands
4. supporting structures:
1.


scrotum
penis
Functions of the Male Reproductive System
1.
2.
3.
4.
5.
Testes produces sperm & the male sex hormone
Testosterone (T)
Ducts transport, store, & assist in maturation of
sperm
Accessory sex glands secrete most of liquid portion
of semen
Penis contains the urethra, passageway for
ejaculation of semen & excretion of urine
Scrotum protects temperature-sensitive testes from
temperature fluctuations
Scrotum
 a supporting structure for the testes
 features:
 loose skin & superficial fascia attached from root of
penis
 externally:

raphe: median ridge that separates scrotum into
right & left sides
 internally:

scrotal septum: divides scrotum into 2 sacs, each
with 1 testes
Scrotum - 2
 features continued:
 dartos muscle: smooth muscle fibers
 contraction causes wrinkled appearance (reduces
heat loss)
 cremaster muscle: skeletal muscle
 2 features regulate temp of testes:
location outside trunk keeps temp 2 – 3 °C lower
than core body temp
2. in response to cold temps, both muscles contract
moving testes closer to body so can absorb body
heat
1.
Testes (plural)/ Testis (singular)
 aka testicles
 paired oval glands develop near kidneys  begin
descent into scrotum thru inguinal canals during
latter half 7th month gestational age
 leading edge covered with peritoneum called tunica
vaginalis

Hydrocele: serous fluid collects between this &
testis (injury or inflammation of epididymis)
Hydrocele
Testes - 2
 tunica albuginea:
internal to tunica vaginalis
 dense irregular CT
 extends inward into testis forming septa: divide
testis into series of 200 – 300 lobules (internal
compartments)
 each lobule contains 1 – 3 coiled seminiferous
tubules : *site of production of semen
 spermatogenesis: process by which seminiferous
tubules produce sperm

Testes
Seminiferous Tubules
 2 types of cells:
spermatogenic cells
1.




sperm-forming cells:
spermatogonia: stem cells  primordial germ cells
arise in yolk sac & enter testes during 5th wk of
development: remain dormant until puberty
1° spermatocytes, 2° spermatocytes, spermatids,
sperm cells (layers of progressively more mature
cells)
2. Sertoli cells

function in supporting spermatogenesis
Spermatogenesis
Sertoli Cells
 aka sustentacular cells
 extend from basement membrane  lumen of tubule
 held together by tight junctions

form obstruction known as the blood-testis
barrier: all substances must pass thru Sertoli
cells to reach developing sperm cells (after
spermatogonia)
Sertoli Cell
Functions of the Sertoli Cells
1.
2.
3.
4.
5.
6.
nourish spermatocytes, spermatids, & sperm
phagocytoze excess spermatid cytoplasm as they
develop into sperm
control movements of spermatogenic cells &
release of sperm into lumen of seminiferous
tubules
produce fluid for sperm transport
secrete hormone inhibin
mediate effects of T & FSH
Leydig Cells
 interstitial cells (between seminiferous tubules)
 *secrete T
Sperm
 ~300 million sperm complete spermatogenesis/d
 ~60 μm long
 once ejaculated last ~48 hours w/in female
reproductive tract
Hormonal Control of the Testes
Ducts of the Male Reproductive System
 fluid secreted by Sertoli cells generates pressure
which pushes sperm & fluid along lumen of
seminiferous tubule  eventually released as
ejaculate
Epididymis
 epi = over or above / didymis = testis
 aka: ductus epididymis
 plural:epididymides
 comma-shaped organ
 lies along posterior border of each testis
ductus epididymis
2. head
3. body
4. tail
1.
Ductus Epididymis
 ~6 m in length
 pseudostratified columnar epithelium lined with
microvilli called stereocilia

increase surface area for reabsorbing degenerated
sperm
 surrounded by smooth muscle
 Function of epididymis:
 *sperm maturation (acquire motility & ability to
fertilize an ovum)
 smooth muscle contraction propels sperm into ductus
deferens
 sperm storage (viable up to several months)
Ductus Deferens/ Vas Deferens
 ascends along posterior border of epididymis 
inguinal canal entering pelvic cavity  loops over
ureter  passes down posterior surface of urinary
bladder
 terminal end is dilated = ampulla
 pseudostratified columnar epithelium
 3 layers smooth muscle (inner & outer layers
longitudinal, middle layer circular)
Function of Vas Deferens
 Function:
conveys sperm from epididymis  urethra by
peristaltic contractions
2. sperm storage (several months)
1.

sperm not ejaculated are reabsorbed
Vasectomy
 main method for sterilization of males
 portion of each vas deferens is cut out & ends ligated
 sperm
production continues but do not reach exterior
 degenerate & destroyed by phagocytes

Ejaculatory Ducts
 formed by union of duct from seminal vesicle &
ampulla of ductus deferens
 pass inferiorly & anteriorly thru prostate gland
 terminate in prostatic urethra where they eject
sperm & seminal vesicle secretions just before the
release of semen from urethra to exterior
Urethra
 shared terminal duct of reproductive & urinary
systems
 passes thru:
prostate
 deep muscles of perineum
 penis

Urethra
 3 parts:
Prostatic Urethra
2. Membranous Urethra
1.

portion thru deep perineal muscles
3. Spongy (penile) Urethra


portion thru corpus spongiosum of penis
ends at external urethral orifice
Parts of Male Urethra
Accessory Sex Glands
 secrete most of liquid portion of semen
 Include:
Seminal Vesicles
2. Prostate
3. Bulbourethral Glands
1.
Seminal Vesicles
 aka seminal glands
 paired, convoluted, pouchlike structures
 posterior to base of urinary bladder (superior
surface) & anterior to rectum
 *secrete alkaline, viscous fluid: (~60% of vol of
semen)
fructose
 prostaglandins
 clotting proteins (different from those in blood)

Seminal Vesicles Fluid
 alkaline to neutralize acidic environment of male
urethra & female vagina (acids inactivate or kill
sperm)
 fructose:used for ATP production in sperm
 prostaglandins contribute to sperm motility &
viability
 clotting proteins help semen clot after ejaculation
Prostate
 single, donut-shaped gland
 ~size of a golf ball
 inferior to urinary bladder
 surrounds prostatic urethra
 increases in size from birth to puberty when it
expands rapidly until ~ age 30, remains stable ~ age
45, further enlargement may occur after that
Prostatic Fluid
 milky, slightly acidic
 ~25% of vol of semen
 empties  urethra thru many prostatic ducts
 contains:
citric acid (ATP production in sperm)
2. several proteolytic enzymes
1.
PSA: prostate-specific-antigen
3. acid phosphatase (function unknown)
4. seminalplasmin: bacteriocidal

Bulbourethral Glands
 aka Cowper’s glands
 pea sized, inferior to prostate gland on either side of
membranous urethra
 ducts open into spongy urethra
 secrete
1. alkaline fluid (protects sperm from acidic
environment of spongy urethra)
2. mucus  lubricates end of penis & lining of urethra
(decreases # of sperm damaged during ejaculation)
Semen
 mixture of sperm &
 seminal fluid
 (secretions of seminiferous tubules, seminal vesicles,
prostate, & Cowper’s glands)
 average vol: 2.5 – 5 mL with 50 – 150 million
sperm/mL
 <20 million sperm per mL probably infertile
 pH: 7.2 – 7.7
 provides sperm with:
1.
transportation medium
2. nutrients
3. protection from hostile acidic environment of male
urethra & female vagina
Penis
 contains urethra
 passageway for urine & semen
 Parts:
Body
2. Glans Penis
3. Root
1.
Body of the Penis
 Corpora Cavernosa:
2 dorsolateral
masses
 Corpus Spongiosum:
 midventral mass
 spongy urethra w/in

Circumcision
 portion of prepuce (fore skin)surgical excised 3 – 4
days after delivery or 8th day for Jewish rite