Histology of

Male
Reproductive
System

Prof.Dr.Bekir Uğur ERGÜR

Aim

• To learn histological structure and the histophysiology of

male reproductive organs
Learning Goals

• To learn the histology and histophysiology of the

testes
• To learn the histology and histophysiology of the
genital ducts
• To learn the histology and histophysiology of the
associated glands:
• Paired seminal vesicles
• Single prostate glands
• Bulbourethral (Cowper) glands
• To learn the histology and histophysiology of the
penis
Male Reproductive
bladder
System
• Primary sex organs
• produce gametes (testes)
seminal vesicle
• Secondary sex organs
• male - ducts, glands, penis vas
prostate gland
deferens
• Secondary sex characteristics
• develop at puberty bulbourethral gland
• pubic, axillary and facial hair,
scent glands, body
morphology and low-pitched urethra
voice in males
• In response to hormones epididymis

testis
penis
Male Genital System
• Two testes..formation of
spermatozoa & synthesis, release and
storage of testosterone
• Genital ducts
• Associated glands..formation of
noncellular portion of semen
• Paired seminal vesicles
• Single prostate glands
• Bulbourethral (Cowper)
glands
• Penis...delivery of semen to female
reproductive system
Testes
• Oval organ, 4 cm x 2.5 cm
• Tunica vaginalis

• Tunica albuginea
• Tunica vasculosa
• Seminiferous tubules
• Tubuli recti
• Rete testis
• Ductus efferentes
• Epididimis
• Ductus deferentes
• Spermatic cord
 Testes
• Septa divide testes into
compartments (250-300
lobules) containing
seminiferous tubules (1-4)
• Tubules lined with thick
germinal epithelium
interstitial cells between
• Tubules - testosterone
• Sustentacular cells
promote sperm cell
development

27-8
 Testes
• The posterior aspect of TA is
thickened to form mediastinum
testis.
• The connective tissue septa
radiate from MT to subdivide
each testis into approx 250
pyramid shaped lobuli testis.
• Each lobule has 1-4 blindly
ending seminiferous tubules
• Richly vascularized and
innervated loose connective
tissue derived from TV
surrounds STs.
• Interstitial cells of Leydig make
groups within this CT.
 Testes
• Seminiferous epithelium of
STs produces spermatozoa.
• Spermatozoa enter tubuli recti
that connect the open end of
each ST to rete testis
(labyrinthine spaces within
MT).
• Spermatozoa leave the RT
through ductuli efferentes
(10-20 short tubules) which
fuse with epididymis.
 Testes: vascular supply
• The vascular supply of each testis is derived from testicular
artery descending with testis into scrotum with ductus deferens
(vas deferens)
• The TA give branches before piercing the capsule to form
intratesticular elts.
• Testicular capillary beds are collected into pampiniform plexus
of veins which are wrapped around the testicular artery
• Artey, veins and the ductus deferens form the spermatic cord.
• PP blood is cooler than TA; reduce the arterial blood
temperature ...form a countercurrent heat exchange system.
Testes temp is kept lower (35 oC)...spermatozoa develop
normally
 Seminiferous tubules

• 30-70 cm long, 150-250 m in diameter highly convoluted tubules

(total1000 STs in two testes, total length 0.5 km)
• Tunica propria (slender CT) and thick seminiferous (germinal)
epithelium make the wall of ST
• A basal lamina separates SE and the TP
• TP contains type 1 collagen bundles housing several layers of
fibroblasts (myoid cells in aimals not humans).
• There are spermatogenic cells and the Sertoli cells within the SE.
 Sertoli cells
• Tall columnar cells, with a basal
clear oval nucleus and complex
infoldings at the apical and lateral
cell membranes
• Contain cytoplasmic inclusions
crystalloids of Charcot-Böttcher
with unknown function
• Cell cytoplasm is filled with SER, has
many mitochondria and a well
developed Golgi apparatus.
• Lat. cell membranes of adjacent
Sertoli cells form occluding
junctions subdividing the lumen of
the ST into narrower basal and the
wider adluminal compartments.
• The ZOs of Sertoli cells establish a
blood-testis barrier that isolates the
adluminal compartment from CT
influences thereby protecting the
developing gametes from the
immune systeme.
 Sertoli cells

-Main cell thypes of

tubules to the puberty
-Irregular corners
(suurounds
developind
spermatocytes)
-zonula ocludens
(basal and adluminal
compartments)
Blood- Testis barriers.
27-14
 Blood-testis barrier
• Sertoli cells form the blood-testis
barrier.
• Basal compartment comprises the
interstitial space and the spaces
occupied by the spermatogonia.
• Adluminal compartment comprises
the tubule lumen and the intercellular
spaces down to the level of the
occluding junctions (OJ). In this
compartment are spermatocytes,
spermatids, and spermatozoa.
• Cytoplasmic residual bodies from
spermatids undergo phagocytosis by
the Sertoli cells and are digested by
lysosomal enzymes.
• Myoid cells surround the seminiferous
epithelium.
 Sertoli cells function in:
• supporting the developing
spermatogenic cells;
• establishing the blood-testis
barrier;
• phagocytosis of cytoplasm
shed by developing
spermatogenic cells;
• manufacturing the following
substances: androgen binding
protein, antimullerian
hormone, inhibin, testicular
transferrin, and a fructose-
rich medium.
 Spermatogenic cells
•Most of the cells composing
the thick seminiferous
epithelium are spermatogenic
cells in various stages of
maturation. Spermatogonia,
are located in the basal
compartment,
•Primary spermatocytes,
secondary spermatocytes,
spermatids,spermatozoa
occupy the adluminal
compartment.
•Spermatogonia are diploid
cells that undergo mitotic
division to form more
spermatogonia, primary
spermatocytes, which migrate
from the basal into the
adluminal compartment.
 Spermatogenesis
• Primary
spermatocytes enter
the first meiotic
division to form
secondary
spermatocytes, which
undergo the second
meiotic division to
form haploid cells
known as
spermatids.
• Spermatids are
transformed into
spermatozoa by
shedding of much of
their cytoplasm,
rearrangement of
their organelles, and
formation of flagella.
 The maturation process
(spermatid....spermatozoa)

• Spermatocytogenesis: spermatogonia differentiate

into primary spermatocytes
• Meiosis: reduction division whereby diploid primary
spermatocytes reduce their chromosome
complement, forming haploid spermatids
• Spermiogenesis: transformation of spermatids into
spermatozoa (sperm)
 Spermatogenesis
• Diagram showing the clonal
nature of the germ cells.
Only the initial
spermatogonia divide and
produce separate daughter
cells.
• Once committed to
differentiation, the cells of
all subsequent divisions stay
connected by intercellular
cytoplasmic bridges.
• Only after they are
separated from the residual
bodies can the spermatozoa
be considered isolated cells.
27-21
 Spermatagonium types
Type A spermatogonium
Out of the
blood-testis
Type B spermatogonium barrier

Primary soermatocyte (4n)

Meiosis I (22 days
in prophase)
Secondary spermatocyte (2n)
Meiosis II (very
fast, no S phase)
Spermatid (n)

No cell division

spermatazoon
 Spermatozoon
• Spermatids discard much of
their cytoplasm and form a
flagellum to become
transformed into
spermatozoa, a process
known as spermiogenesis.
• Spermatozoa (sperm) are
long cells (~65 μm),
composed of a head, housing
the nucleus, and a tail, which
accounts for most of its
length
• Tail of the spermatozoon is
subdivided into four regions:
neck, middle piece, principal
piece, and end piece. The
plasmalemma of the head is
continuous with the tail’s
plasma membrane.
 Spermatozoon
• Neck (~5 μm long) connects the
head to the remainder of the tail. It
is composed of the cylindrical
arrangement of the nine columns of
the connecting piece that encircles
the two centrioles, one of which is
usually fragmented. The posterior
aspects of the columnar densities
are continuous with the nine outer
dense fibers.
• Middle piece (~5 μm long) is located
between the neck and the principal
piece. It is characterized by the
presence of the mitochondrial
sheath, which encircles the outer
dense fibers and the centralmost
axoneme. The middle piece stops at
the annulus. Two of the nine outer
dense fibers terminate at the
annulus; the remaining seven
continue into the principal piece.
 Spermatozoon
Principal piece (~45 μm long)
is the longest segment of the
tail and extends from the
annulus to the end piece. The
axoneme of the principal
piece is continuous with that
of the middle piece.
Surrounding the axoneme are
the seven outer dense fibers
that are continuous with
those of the middle piece
and are surrounded, in turn,
by the fibrous sheath.
End piece (~5 μm long) is
composed of the central
axoneme surrounded by
plasmalemma. The axoneme
is disorganized in the last 0.5
to 1.0 μm.
 Leydig cells
• Luteinizing hormone (LH), a gonadotropin
released from the anterior pituitary
gland, binds to LH receptors on the Leydig
cells, activating adenylate cyclase to form
cyclic adenosine monophosphate (cAMP).
Activation of protein kinases of the Leydig
cells by cAMP induces inactive
cholesterol esterases to become active
and cleave free cholesterol from
intracellular lipid droplets. The first step
in the pathway of testosterone synthesis
is also LH-sensitive because LH activates
cholesterol desmolase, the enzyme that
converts free cholesterol into
pregnenolone.
• The various products of the synthetic
pathway are shuttled between the
smooth endoplasmic reticulum and
mitochondria until testosterone, the
male hormone, is formed and is
ultimately released by these cells.
 Leydig cells

Interstitial cells and cells

of the seminiferous
epithelium. H&E stain.
High magnification.
Hypophyseal control of male reproduction
• Luteinizing hormone (LH)
acts on the Leydig cells,
• Follicle-stimulating
hormone (FSH) acts on
the seminiferous tubules.
A testicular hormone,
inhibin, inhibits FSH
secretion in the pituitary.
 Intratesticular genital ducts

• Tubuli recti
• Rete testis

•Connect seminiferous tubules to epididymis

Spermatic Ducts
SEMİNİFEROUS TUBULES

TUBULI RECTI

RETE TESTIS

DUCTUS EFFERNTES

EPIDIDIMIS

DUCTUS DEFERENTES
 Tubuli recti
• Short, straight tubules
delivering spermatozoa from
the seminiferous tubules into
rete testis.
• Lined by Sertoli cells in their
first half near the ST
• Formed by seminiferous
epithelium, lined by a simple
cuboidal epithelium in their
second half near the rete
testis
• Cuboidal cells have short
stubby microvilli and most
have a single flagellum
 Rete testis

• Consists of labyrinthine
spaces lined by a simple
cuboidal epithelium within
the mediastinum testis.
• Cuboidal cells resemble
those of tubuli recti; have
numerous short microvilli
with a single flagellum
• Immature spermatozoa pass
from tubuli recti into rete
testis
 Ductuli efferentes
• 10-20 short tubules that drain
spermatozoa from the rete testis
andpierce the tunica albuginea of
testis to conduct the sperm to
epididymis
• Simple epithelium contains
noncilliated cuboidal cells or cilliated
columnar cells
• Cillia of the columnar cells move the
spermatozoa toward the epididimis
• Cuboidal cells having many
lysososomes and apical
plasmolemmal invaginations are
responsible of endocytosis (resorb
most of the luminal fluid)
• Epithelium sits on a BL that separates
it from the thin loose CT wall of each
ductule
• CT is surrounded by a thin layer of
circularly arranged smooth muscle.
 Extra testicular genital
ducts***
• Epididymis
• Ductus deferens
• Ductus ejaculatorius
 Epididymis
• Secrete numeruous factors that facilitate
the maturation of spermatozoa; but
spermatozoa cannot fertilize a secondary
oocyte untill they undergo capacitation; a
process trigered by secretions produced
in female genital system.
• Is a thin, long (4-6 m), highly convoluted
tubule consisting of a head, body and tail.
• The lumen is lined by pseudostratified
epithelium composed of two cell types:
short basal cells ;stem cells and the tall
principal cells, resorbing the luminal fluid
and manifacturing
glycerophosphocholine (a glycoprotein
that inhibits spermatozoon capacitation
preventing spermatozoon from fertilizing
a secondary oocyte untill the sperm
enters the female genital tract)
 Ductus deferens (Vas deferens)
• Each DF is a thick walled muscular
tube with a small irregular lumen
that conveys the spermatozoa from
the tail of the epididimis to the
ejaculatory duct.
• Mucosa formed by
pseudostratified columnar
epithelium (principal cells are
shorter) with stereocilia and a
lamina propria.
 Extra testicular genital ducts
• The dilated terminus of each
ductus deferens is known as
ampulla

• As the ampula approaches

the prostate gland it is joined
by seminal vesicle.
• The continuation of the
junction of the ampulla with
the seminal vesicle is known
as ejaculatory duct.
 Ejaculatory duct
• Ampulla of ductus deferens
joins the seminal vesicle to
form ejaculatory duct; which
then enters the prostate
gland and opens in the
prostatic urethra at the
colliculus seminalis.
• Is a short straight tubule
• Lumen is lined by simple
columnar epithelium
• Subepithelial CT is folded
• Has no smooth muscle in its
wall.
 Accessory genital glands

•Paired seminal vesicle

•Single prostate gland
•Paired bulbourethral
glands
 Seminal vesicles

• This gland produces a viscose yellow fructose rich seminal fluid that
makes 70% of the volume of the semen. It is the source of the enery
for the spermatozoa.
• The characteristic pale yellow colour of semen is due to the
lipochrome pigment released by seminal vesicles
 Prostate
• Is the largest of the accessory
glands, is pierced by the urethra
and the ejaculatory ducts.
• Is a conglomeration of 30 to 50
individual compound
tubuloalveolar glands,
• is arranged in three discrete,
concentric layers mucosal,
submucosal, and main.

• Components of prostate
gland are lined by a simple to
pseudustratified to columnar
epihelium; surrounded by
connective tissue and
smooth muscle.
 Prostate

• Distribution of its
glands in 3 zones. The
gland ducts open into
the urethra.
Prostatic secretion

• Constitutes a part of semen.

• Is a serous, white fluid rich in
lipids, proteolytic enzymes,
acid phosphatase,
fibrinolysin, and citric acid.
• Formation, synthesis, and
release of the prostatic
secretions are regulated by
dihydrotestosterone, the
active form of testosterone
 Bulbourethral (Cowper’s) glands

• Paired small (3-5 mm diam)

glands located at the root of
penis, just just at the beginning
of membranous urethra
• Epith of these compound
tubuloalveolar glands varies from
simple cuboidal to simple
columnar
• The secretion is a thick slippery
fluid that lubricate the lumen of
the urethra
 Penis
• Is composed of three columns of erectile
tissue, each enclosed by its own dense,
fibrous connective tissue capsule, the
tunica albuginea.
• Two of the columns of erectile tissue, the
corpora cavernosa, are positioned
dorsally; their tunicae albugineae are
discontinuous in places, permitting
communication between their erectile
tissues.
• Third column of erectile tissue, the
corpus spongiosum, is positioned
ventrally. Because the CS houses the
penile portion of the urethra, it is also
called the corpus cavernosum urethrae.
• CS ends distally in an enlarged, bulbous
portion, the glans penis (head of the
penis). The tip of the glans penis is
pierced by the end of the urethra as a
vertical slit.
Penis