Male Reproductive System
Male reproductive system consists of:
1. The testes surrounded by tunica vaginalis,
2. The epididymis,
3. The ductus deferentes/ductus deferens,
4. The accessory glands (vesicular, prostate, and bulourethral),
5. The urethra, and
6. The penis surrounded by the prepuce.
Histology of Testis
• Covered by Tunica albuginea,
• Convoluted Seminiferous Tubules, and
• Interstitial cell/Leydig cell.
Histology of Testis-Tunica albuginea
 It is a solid capsule of dense
connective tissue.
 Consist of collagen fiber, elastic
fibers and myofibroblasts.
 In cat, interstitial endocrine cells
(secretes testosterone) also
found in the tunica albuginea.
Histology of Testis- Seminiferous Tubules
Convoluted seminiferous tubules:
Tortuous two ended loops with a
diameter between 150-200 μm.
 The seminiferous tubules have 3
components:
1. Lamina propria
2. Somatic cells (Sustentacular, Supporting,
or Sertoli,s cells)
3. Spermatogenic cells.

1. Lamina Propria of Seminiferous Tubules
 The
lamina propria surrounds the
seminiferous tubules and consists of
collagen and elastic fibers.
 Peritubular smooth muscle (in boar), and
myofibroblast (in bull) present which cause
contraction of seminiferous tubules for the
ejection of spermatozoa.
Lymphocytes and monocytes are also
present in the lamina propria.
2. Sertoli Cells of the Seminiferous Tubules
2. Sertoli Cells of the Seminiferous Tubules
 Also known as Sustentacular cell/
Supporting cell.
 These cells are resting on the base of
seminiferous tubules and having large
nucleus with one prominanat nucleoli.
 The cells are irregularly outlined,
elongated cells.
 Sustentacular cells are closely
associated with the spermatocytes, and
spermatids.
Function of Sertoli Cells
Important functions of Sertoli cells:
• Nutritive, Protective and Supportive functions for the
spermatogenic cells.
• Phagocytize regressive and spermatogenic cells.
• Detached residual bodies of spermatid.
• They mediate the action of FSH and testosterone on the
germ cells.
• They secretes inhibin which blocks the secretion of
pituitary-FSH.
3. Spermatogenic Cells of Seminiferous
Tubules
Spermatogenic cells are:
1. Spermatogonia: They are spherical
cells resting on the basement memb-rane with round one or two nuclei.
The cells are located in between Serto-li cells. There are two types of sperma
-togonia. Type A and Type B. Type B
undergoes mitosis and differentiated
into primary spermatocyte.
2. Primary spermatocytes, secondary
spermatocytes, and spermatids are
the next generation of the spermatogonia.
Histology of Testis- Interstitial Cell/Leydig cell
The intertubular space
contain loose connective tissue, blood and
Lymph vessels,fibrocyte
Free mononuclear
cells, and interstitial
endocrine (Leydig)
cells.
Interstitial or Leydig cells of the testis
• Embryologically interstitial cells develop from
mesenchymal cells.
• Interstitial cells comprises 1% of the entire
testicular volume in the adult ram, 5% in the
bull, and 20-30% in the boar.
• These cells found in the form of cords or
clusters. The cells are spherical with large
round cells, enough endoplasmic reticulum and
mitochondria for the transformation of
cholesterol (important component of the
testosterone hormone).
Function of Interstitial or Leydig cells
of the testis
• Promote normal sexual behaviour of male
animals.
• Growth, maintenance, and initiate function of
the male accessory glands and secondary sex
characters.
• Control spermatogenesis.
• General anabolic effect.
Spermatogenesis
Definition:
It is the process of formation of spermatozoa from
spermatogonium. Usually one mitotic and two meiotic stage
occurs during the process. The sequence of event takes place
by 3 successive process:
1. Spermatocytogenesis: In this process spermatogonia
developed into primary spermatocytes. From 1 Bspermatogonium 1 primary spermatocytes formed (by
mitosis).
2. Meiosis: By 2 meiotic division 1primary spermatocyte
divide into 2 secondary spermatocyte and then finally into 4
haploid spermatid.
3. Spermiogenesis: Transformation of spermatid into
spermatozoa.
Images for Spermatogenesis
Morphology of Bull Spermatozoa
Head
Neck
Middle Piece
Principal Piece
Tail
Spermatozoa is a single cell
having nucleus (head),
cytoplasm and cell membrane
around the centriole and
axonema (tail).
It consist of Head, Neck, and
Tail. Neck is short. Tail is
further divided into: Middle
piece, Principal piece and End
piece. Middle piece is
characterized by the presence
of Mitochondria for energy
during motility. The principal
piece is the longest. Tail is the
terminal part.
Histology of Epididymis
The ductus epididymis is extremely tortuous
and coiled. In bull and boar the length is 40
meter, and in stallion it is 70 meter in length.
 Epididymis is lined by a pseudostratified
epithelium, surrounded by a small amount of
Loose connective tissue and circular smooth
muscle fiber.
 Two cell types are present: tall columnar
ciliated cells (principal cells) and short
absorptive cells.
Function:
Storage and maturation of the spermatozoa.
Histology of Ductus Deferens
 The
mucosa is lined by
Pseudostratified
columnar epithelium.
 Lamina propria consist
of loose connective
tissue.
 Propria submucosa in
Stallion, bull and boar
have circular,
longitudinal, and oblique
Smooth muscle layers.
The terminal portion of the ductus deferens contains simple branched
Tubulo-alveolar gland in the proria-submucosa. In the stallion, bull, and ram
these glands occupy the entire propria-submucosa surrounded by smooth
muscle, whereas, in dog the gland is not surrounded by muscles. The gland is
lined by simple cuboidal to columnar epithelium. In man no such type of gland.
Male Accessory Gland
• Male accessory glands of animals are:
1. Vesicular gland or Seminal vesicle
2. Prostate gland
3. Bulbourethral gland
Histology of Vesicular Gland
• The paired vesicular gland is a compound tubular or
tubulo-alveolar gland.
• The glandular epithelium is pseudostratified with tall cell.
• Lamina propria-submucosa is continuous.
• Tunica muscularis is of smooth muscle and it is followed
by tunica serosa or adventitia.
Images for Vesicular Gland of Animals
Vesicular Gland in Different Animals
• Stallion
• Epithelium is
Pseudostratified.
• It is true vesicular.
• Interlobular septa is thin
irregularly arranged
muscles.
Boar
Same as stallion
Vesicular
Smooth
muscle is few
in the interlobular
septa.
Ruminants
Columnar cell
Gland is compact.
The interlobular septa
is thick with predominant
smooth muscle.
Histology of Prostate Gland
• Tubulo-alveolar gland derived from the epithelium of
pelvic urethra.
• Having two parts: 1. Compact or External portion (corpus
prostate), and internal portion (pars disseminate). The
external portion entirely surrounds part of the pelvic
urethra. The disseminate portion is located in the
propria-submucosa of the pelvic urethra.
• The secretory tubules/alveoli is lined by a simple
cuboidal or columnar epithelium.
Histology of Prostate Gland-cont
• Occasionally, concentriclly laminated concretions of secretory
materials are found in the tubules of the alveoli.
• The prostate is surrounded by a capsule of dense irregular
connective tissue that contain many smooth muscle.
• From the capsule connective tissue and smooth muscle
enters the gland and divide the gland into lobes and lobules.
Therefore aound the small secretory unit there is connective
tissue and smooth muscle, contraction of which empties the
secretory materials into the duct system.
•
•
Images for Prostate Gland of Animals
Prostate Gland in Different Animals
• Carnivors
• External portion is
well developed
and separated into
2-lobes. The Internal
portion consist of few
glandular lobules.
Stallion
Only external
portion is
present. No
internal gland.
Ruminants
Boar
The external
portion is
absent. Internal
portion is well
developed and
encircles the
uretra.
The
external
portion
is plate
like and
internal
portion is
well
developed.
Histology of Bulbourethral Gland
• Paired gland, and located dorsolaterally from the bulbar portion
of the urethra. It is compound tubular (boar, cat, and buck) or
tubulo-alveolar (stallion, bull, ram). It is absent in dog.
• The secretory portion of the gland are lined with a tall simple
columnar epithelium and occasional basal cells.
• The gland is covered by a fibroelastic capsules with striated
muscle.
• Trabeculae extending from the capsule into the gland and
devide it into many lobes and lobules. Trabeculae consists of
both smooth and striated muscle.
Images for Bulbourethral Gland of
Animals
Bulbourethral Gland in Different
Animals
• Carnivors
Stallion
Ruminants
In the cat, the
The gland
Same as
sinus like duct
is completely stallion
and short, narrow surrounded by
unbranched tubular bulbocavernous
end piece.
Muscle.
Histology of Penis of Different Animals
• Penile muscles are two types:
• Corpus cavernosum penis and
• Corpus spongiosum.
Corpus cavernosum penis muscle: Paired muscle
originates from ischiatic tuberosities and situated
dorsal to the urethra of animals.
 Covered by tunica albuginea of connective tissue.
 Trabeculae enters the muscle as numerous septa.
 There are numerous cavernous space within this
muscle, lined by endothelium, and are filled up by
blood during erection.
Histology of Penis of Different
Animals- cont.
• Corpus spongiosum penis muscle:
This muscle is situated around the urethra.
Note please:
• Corpus cavernosum muscle is thicker and spacious than
the spongiosum muscle.
• In the horse Corpus cavernosum muscle is more thicker
and spacious than the ruminants.
• In the dog os penis (bones of the penis) is present in
the glans.
• In the cat the glans is provided with the spines.
Mechanism of Erection of Penis
• Erection of penis depends on the pheromonal (in insect and
lower animals), psychological, neurological, and blood flow into
the penis.
• Relaxation of the muscles of helicine arteries of the penis causes
increased blood flow into the penis and cavernous spaces
resulting increases in the length of penis, which compress the
veins and subsequently decreases the outflow resulting
persistent of the erection of penis until semen ejaculation.
• Detumescence is initiated by contraction of the musculature of
the helicine arteries and thus decrease in arterial inflow causes
the penis to return to flaccid state.
•
High sugar and cholesterol level of the blood decrease inflow of
blood resulting erectile dysfunction of man and animals.