MALE REPRODUCTIVE SYSTEM PRESENTATION.ppt

MALE REPRODUCTIVE
SYSTEM
5/2/2023 1

Introduction
• It is comprised of a pair of testes, bilateral
duct system, accessory sex glands, urethra
and the penis.
• The duct system includes tubuli recti, rete
testis, efferent duct, epididymis duct,
deferens duct, and ejaculatory duct.
• Accessory sex gland include seminal
vesicles, prostate gland, and bulbourethral
(Cowper’s) gland.
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The Testes
• These are the primary male gonads that are
suspended in the scrotum and their main
function is production of spermatozoa and
secretion of male hormones (Androgens).
• The left testis is lower than the right and
each testis measures about 4 to 5 cm long,
2.5 cm width and 3 cm in thickness and each
weighs 10.5 to 14 gms.
5/2/2023 3

Testes cont…...
• Structural organization
– Each testis is contained in one compartment of
the fibromuscular sac known as scrotum.
– The scrotum has two right and left compartments
that are separated externally by a cutaneous
raphe that continues ventrally to the inferior
surface of the penis and dorsally to the anus
through the perineum.
5/2/2023 4

Testes cont…...
– The scrotum is made up of the skin, smooth
muscle (dartos muscle, cremaster muscle),
external spermatic fascia, cremasteric fascia
and the internal spermatic fascia which is
associated with the external covering of the
testis the tunica vaginalis
– Testis is immediately surrounded by the
testicular capsule, which is composed of three
layers:
–Outer layer or tunica vaginalis
–Middle layer or tunica albuginea
–Innermost layer or tunica vasculosa
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Tunica vaginalis
• Is the lower end of the peritoneal processus vaginalis
which precedes the descent of the fetal testes from
the abdomen to the scrotum that has lost connection
with the peritoneal cavity.
• It covers the anterior and lateral surfaces of the
testes.
• Has visceral and parietal layers.
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• Visceral layer covers all aspects of the
testes except the posterior border.
• Parietal covers the posterior aspect of the
testes.
• In between them there is a cavity that
contain small amount of fluid.
• Sometimes during pathological situations
abnormal fluid accumulation occurs in the
cavity leading to hydrocoele.
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tunica albuginea
• A thick layer of dense fibroelastic connective
tissue that contains some smooth muscle cells
concentrated predominantly on the posterior
aspect of the testis adjacent to the epididymis to
form the mediastinum testis from which arises
septae (septula testis) that divides the testis into
compartments or lobules.
• Each lobule is pyramidal in shape with the apex
directed towards mediastinum.
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• There are about 250 lobules each containing
1 to 4 seminiferous tubules and a connective
tissue stroma in which intestitial cells
(Leydig cells) are located.
• Completely covers the testes. It lies internal
to the tunica vaginalis.
5/2/2023 11

tunica vasculosa
• The innermost layer of testicular capsule
that consists of a network of blood vessels
embedded within a delicate loose
connective tissue.
5/2/2023 12

Histological aspect
• Consist of many seminiferous tubules embedded
in relatively sparse interstitial tissue.
• The tubules are lined by a simple columnar
epithelium of Sertoli cells.
• Interspersed within the tubular epithelium are
germ cells.
• Meiotic cell divisions lead from spermatogonia
through primary and secondary spermatocytes to
cells called spermatids, which mature into
spermatozoa.
5/2/2023 13

• Interstitial tissue between the tubules
contains clusters of endocrine Leydig cells
which secrete testosterone.
• All of the seminiferous tubules converge
onto a network of interconnecting tubules,
the rete testis, which in turn lead through
numerous small efferent ductules into the
larger duct which extends through the
epididymis.
5/2/2023 14

Seminiferous tubule
• Highly convoluted tubule about 0.2 mm in
diameter and 30 to 40 cm long.
• Are lined by seminiferous epithelium which is a
modified stratified cuboidal epithelium consisting
of spermatogenic cells and supporting cells (sertoli
cells).
• The tubules are surrounded by a basal lamina and
by the thin 3 to 4 squamous smooth muscle cells
invested by their own basal (external) lamina.
5/2/2023 16

• The connective tissue aspect of the smooth
muscle cells is covered by the thin
endothelium of a vast system of large
lymphatic capillaries.
• This system and smooth muscle sheath
represent a physiological barrier to blood-
borne substances intended to reach the
spermatogenic cells.
5/2/2023 17

• Spermatogenic (Germ) cells
• Comprises a stratified layer of epithelium 4
to 8 cells deep, lining the seminiferous
tubule.
• The cells differentiate progressively from
the basal region of the tubule to the lumen.
5/2/2023 18

• Proliferation pushes the cells toward the
lumen, and those nearest the lumen
transform into spermatozoa and detach from
the epithelium coming to lie free within the
lumen.
• The sequence of events is referred to as
spermatogenesis (spermatocytogenesis and
spermiogenesis).
5/2/2023 19

• Spermatogonia are the first cells of
spermatogenesis.
• They are always in contact with the basal lamina
of the tubule.
• Two types of spermatogonia can be distinguished:
Type A spermatogonia
– Have a rounded nucleus with very fine
chromatin grains and one or two nucleoli. They
are stem cells which divide to form new
generations of both type A and type B
spermatogonia.
5/2/2023 20

• Type B spermatogonia
– Have rounded nuclei with chromatin
granules of variable size, which often
attach to the nuclear membrane, and one
nucleolus.
– Although type B spermatogonia may
divide repeatedly, they do not function as
stem cells and their final mitosis always
results in the formation of primary
spermatocytes.
5/2/2023 21

• Primary spermatocytes
– Larger than the spermatogonia.
– They are spherical or ovoid in outline,
and are the largest germ cells seen within
the seminiferous tubule where they
occupy the middle zone of the
epithelium.
– A large number of primary spermatocytes
is always visible in cross-sections
through seminiferous tubules.
5/2/2023 22

• Secondary spermatocytes,
– Are smaller than primary spermatocytes.
They rapidly enter and complete the
second meiotic division and are therefore
seldom seen in histological preparations
since they are short lived and divide
quickly to produce Spermatids.
5/2/2023 23

• Spermatids,
– Lie in the luminal part of the
seminiferous epithelium.
– They are small (about 10 µm in
diameter) with an initially very light
(often eccentric) nucleus.
– The chromatin condenses during the
maturation of the spermatids into
spermatozoa, and the nucleus becomes
smaller and stains darker.
– The differentiation of the newly formed
spermatids results into Spermatozoa.
5/2/2023 24

• Spermatozoa
– The mature human spermatozoon is about
60 µm long and actively motile. It is
divided into head, neck and tail.
5/2/2023 25

Sertoli cells
• Constitute true epithelium of the seminiferous
epithelium.
• Relatively few in number spaced along the tubule
at fairly regular intervals crowded between germ
cells.
• They are columnar, tall, pillar-like cells, with their
bases resting on upon the basal lamina.
• Do not migrate nor do they replicate after puberty.
5/2/2023 26

• Interstitial tissue
– It’s the loose connective tissue between
the seminiferous tubules contains
interstitial endocrine cells (Leydig cells),
blood, and lymphatic vessels, nerves,
fibroblasts and mast cells.
• Leydig cells (15-20 µm), located in the
interstitial tissue between the convoluted
seminiferous tubules, constitute the
endocrine component of the testis. They
synthesize and secrete testosterone.
5/2/2023 27

• Active Leydig cells are large ,irregularly
polygonal, acidophilic cells often filled lipid
droplets.
• Have an elaborate smooth endoplasmic
reticulum and mitochondria with
tubulovesicular cristae.
• Inactive cells are difficult to distinguish
from fibroblast.
5/2/2023 28

Male genital ducts
• Two types of ducts
– Intratesticular genital ducts.
Tubuli recti, rete testis, proximal part of
efferent duct.
– Extratesticular genital ducts.
Distal part of efferent duct, epididymis
duct, deferens duct, and ejaculatory duct.
5/2/2023 31

• Tubuli recti
– The straight tubules which is a short
terminal section of seminiferous tubule
that lined solely by Sertoli cells.
– As it narrows towards to rete testis the
lining changes to a simple cuboidal
epithelium.
5/2/2023 32

• rete testis
– Complex series of interconnecting
channels in a highly vascular of
mediastinum testis.
– Lined mainly by low cuboidal epithelium.
– Each cuboidal cell has a single cilium on
its apical surface with a few apical
microvilli.
5/2/2023 33

Efferent duct
• Approx 15 efferent ductules leaves the testis by
penetrating tunica albuginea and connect the testis
to ductus epididymis.
• As it leaves the testis 15 to 20 cm long become
highly coiled and tightly parked into 6 to 10
conical masses called Coni vasculosi.
5/2/2023 34

• At the base of the coni they empty into the
single channel of ductus epididymis
• They are lined with alternating clumps of
tall and short pseudo stratified columnar
cells thus giving rise to the saw-toothed
appearance of the luminal surface.
5/2/2023 35

• Tall columnar cells are ciliated
• Short non-ciliated columnar cells with
numerous microvilli and canalicular
invagination of apical surface.
• Between the columnar cells there are few
basal cells and intraepithelial lymphocytes.
• Has circular smooth muscle layers in the
wall of the ductule.
• Elastic fibers are interspersed among the
muscle cells.
5/2/2023 36

ductus epididymidis
• About 6 m long.
• It is lined by a very tall pseudostratified
columnar epithelium.
• Most cells of the epithelium, also called
principal cells, have long stereocilia.
• Stereocilia are non-motile structures, which
in the EM resemble large microvilli.
5/2/2023 37

• Towards the basal lamina we see a number
of small nuclei, which belong to the basal
cells of the ductus epididymis. These cells
regenerate the epithelium.
• Peristaltic contractions of smooth muscle
cells surrounding the ductus epididymis
move the spermatozoa towards the middle
segment of the duct, which is the site of
final functional maturation of the
spermatozoa - now they are motile.
5/2/2023 38

• The terminal segment of the ductus
epididymis is the site of storage of the
mature spermatozoa.
• Smooth muscle fibers of the terminal part of
the ductus epididymis do not contract
spontaneously.
• They contract during sexual stimulation
concurrently with the contraction of the
musculature of the duct into which it opens,
the vas deferens.
5/2/2023 39

Vas deferens (ductus deferens)
• Connects epididymis to the prostatic urethra
• The mucosa of the vas deferens forms low
longitudinal folds.
• It is lined by a pseudostratified columnar
epithelium. Similar to the epididymis, cells have
long stereocilia.
• The lamina propria is unusually rich in elastic
fibres.
5/2/2023 42

• The muscularis is well developed (up to 1.5
mm thick) and consists of a thick circular
layer of smooth muscle between thinner
inner and outer longitudinal layers.
• The muscularis is the structure which makes
the vas deferens palpable in the spermatic
cord.
• The vas deferens is surrounded by an
adventitia, which is slightly denser than
usual.
5/2/2023 43

• Ejaculatory duct
• The short duct (1 cm) formed by the union
of the ductus deferens and duct of seminal
vesicle.
• It enters the urethra at the prostatic utricle.
• Lined with a simple columnar and
pseudostratified columnar epithelium
• Has no muscle no muscle coat.
• Supporting wall is fibrous connective tissue
only.
5/2/2023 46

Male Accessory Reproductive
Glands
• Consists of
– The seminal vesicles,
– The prostrate and
– The bulbourethral glands.
5/2/2023 47

Seminal vesicles
• They are paired.
• Are elongate sacs (about 4 cm long and 2 cm
wide), highly folded tubular glands with a
muscular and fibrous coat.
• They develop as evaginations of the vas deferens
distal to ampulla.
• They are situated posterior to prostate gland.
• Each consists of one coiling tube (about 15cm
long).
5/2/2023 48

• The mucosa is thrown into various primary,
secondary and tertiary folds that increase
the secretory surface.
• The folds project into the lumen and merge
with one another as a result different
compartments of various sizes are formed.
All communicate with the lumen.
• The muscularis consists of inner circular
and outer longitudinal layers of smooth
muscle.
5/2/2023 49

• The epithelium is variable appearing as
simple columnar or pseudostratified
columnar (columnar cells and basal cells).
• Pseudostratified columnar epithelium
contains tall non ciliated columnar cells and
short round cells that rest on basal lamina
• The lamina propria of the mucosa is fairly
thin and loose.
5/2/2023 50

• They are glands, whose secretion
constitutes 60-70 % of the ejaculate.
• The secretory product of the columnar cell,
which may be seen in the lumen of the
seminal vesicles, is strongly acidophilic.
• It contains large amounts of fructose which
the spermatozoa utilise as a source of
energy.
5/2/2023 51

• The secretion also contains prostaglandins,
flavins (yellow fluorescing pigment - of use
in forensic medicine to detect semen stains)
and several other proteins and enzymes.
• The cocktail of compounds which is
released by the seminal vesicles in addition
to fructose has three main functions:
5/2/2023 52

1. formation of the sperm coagulum,
2. regulation of sperm motility and
3. suppression of immune function in the
female genital tract.
5/2/2023 53

Prostate
• The prostate is the largest accessory sex gland in
men (about 2 × 3 × 4 cm).
• It surrounds the proximal urethra at its origin from
the bladder
• It contains 30 - 50 tubuloalveolar glands, which
empty into 15 - 25 independent excretory ducts.
These ducts open into the urethra.
• The glands are embedded into a fibromuscular
stroma, which mainly consists of smooth muscle
separated by strands of connective tissue rich in
collagenous and elastic fibers.
5/2/2023 56

• The muscle forms a dense mass around the
urethra and beneath the fairly thin capsule
of the prostrate.
• The secretory alveoli of the prostate are
very irregularly shaped because of papillary
projections of the mucosa into the lumen of
the gland.
• The epithelium is cuboidal or columnar also
patches of squamous.
5/2/2023 57

• Basal cells are again present, and the
epithelium may look pseudo stratified
where they are found.
• The secretory cells are slightly
acidophilic and secretory granules may
be visible in the cytoplasm.
5/2/2023 58

• The secretion of the prostate contains citric
acid, the enzyme fibrinolysin (liquefies the
semen), acid phosphatase, a number of
other enzymes and lipids.
• The secretion of the prostate is the first
fraction of the ejaculate.
• The secretory ducts of the prostate are lined
by a simple columnar epithelium, which
changes to a transitional epithelium near the
openings of the ducts into the urethra.
5/2/2023 59

• A characteristic feature of the prostate is the
appearance of corpora amylacea in the secretory
alveoli.
• They are rounded eosinophilic bodies.
• Their average diameter is about 0.25 to 2 mm).
• They appear already in the seventh month of foetal
development.
• Their number increases with age - in particular
past 50.
• They may undergo calcification. Corpora
amylacea may appear in semen.
5/2/2023 60

• Macroscopically the prostrate can be
divided into lobes, but they are
inconspicuous in histological sections.
• In good histological sections it is possible to
distinguish three concentric zones, which
surround the prostatic part of the urethra.
• The peripheral zone contains large, so-
called main glands, whose ducts run
posteriorly to open into the urethra.
5/2/2023 61

• The internal zone consists of the so-called
submucosal glands, whereas
• The innermost zone contains mucosal glands.
• This subdivision of the prostate is of clinical
importance.
• With age the prostate becomes enlarged due to
benign nodular hyperplasia or benign prostatic
hypertrophy.
• The onset age of these hyperplastic changes is 45.
About 3/4 of the males above 60 are affected of
which half will be symptomatic.
5/2/2023 62

• This condition affects the mucosal glands.
• Cancer of the prostate, which is the
second most common malignant tumor in
western males, involves the peripheral zone.
• It affects approximately 1 in 20
• It is often not detected early because the
abnormal growth may not impinge on the
urethra and produce symptoms that demand
prompt attention
5/2/2023 63

Bulbourethral gland (Cowper’s glands)
• Are paired bodies, each the size of a pea,
located in the connective tissue behind the
membranous urethra and joins the initial
portion of penile urethra
• The glands are compound tubuloalveolar
glands that structurally resemble mucus
secretory glands
• Is surrounded by thin connective tissue
capsule, external to which are skeletal
muscle fibers
5/2/2023 67

• The septa pas into the gland to divide it into
lobules
• The secretory end pieces are variable, being
either alveolar, saccular or tubular
• The secretion is clear, mucus like
containing considerable amounts of
galactose, galactosamine, galacturonic acid,
sialic acid and methylpentose.
• They constitute major portion of preseminal
fluid and probably serves as a lubricant of
the penile urethra
5/2/2023 68

semen
• Is a combined product of all of the
glandular elements of the male reproductive
system
• It contains fluid and sperm from the testis
and secretory products from epididymis, vas
deferens, prostate, seminal vesicle and
bulbourethral glands
• It is alkaline in nature
5/2/2023 69

• May help to neutralize the acid environment
of the urethra and vagina
• Also contains prostaglandins that may
influence sperm transit in both male and
female reproductive tracts, and also may
have a role in implantation of a fertilized
ovum
5/2/2023 70

• The volume of average ejaculate of semen
is about 3mL. This is normally contains up
to 100million sperm/mL.
• Of which it is estimated that 20% are
morphologically abnormal; and nearly 25%
are immotile
5/2/2023 71

PENIS
• An elongated organ which is common termination
of both the urinary and genital extratesticular duct
system
• Urethra carries both semen and urine to the
exterior
• It consist primarily of two dorsal masses of
erectile tissue; the corpora cavernosa, and a
ventral mass of erectile tissue that surrounds the
urethra; corpus spongiosum (corpus cavernosum
spongiosum urethrae)
5/2/2023 72

• A dense fibroelastic layer , the tunica
albuginea, binds the three cavernosa
together as well as forming capsule around
each one
• Corpora cavernosa are lined with vascular
endothelium thus increase in size and
rigidity by filling with blood principally
derived from helicine arteries
5/2/2023 73

• These arteries dilate under sexual
stimulation to increase blood flow to the
penis
• Helicine arteries(dilate) and arteriovenous
anastomosis (closes)
• As erectile tissue fills, the peripheral veins
that drain it are increasingly compressed,
this may amplify erectile response
5/2/2023 74

• Thin skin of penis is loosely attached to the
underlying connective tissue which contain
no adipose tissue. Only at the glans penis
skin is firmly attached
• Thin layer of smooth muscle in the skin is
continuous with dartos layer of scrotum
• In uncircumcised male, glans is covered
with a fold of skin, prepuce, which has
characteristic of mucous membrane on its
inner aspect
5/2/2023 75

• Skin contains small sweat glands and
infrequent sebaceous glands unassociated
with hair follicles. No hair follicles on the
distal part of the penis
• On the glans penis and inner surface of
prepuce there are numbers of modified
sebaceous glnds , the Glands of Tyson
5/2/2023 76

• Innervation; spinal, sympathetic, and
parasympathetic
5/2/2023 77

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