Male Reproductive System
IT IS PRESENTED BY : TAGHREAD BARAK ALTHUBYANI
UNDER THE SUPERVISION OF DR.: KHADIJA ABDUL -JALIL FADL AL-DIN
• The male reproductive system
consists of the testes
suspended in the scrotal sacs,,
genital ducts, accessory
glands, and penis
• Testes produce sperm and
testosterone
• The genital ducts and
accessory glands produce
secretions required for sperm
activity
• The secretions from the penile
urethra to provide nutrients
for sperms
Testis
• Testis is CYTOGENOUS GLANDS(secretes living cells) , Mixed gland (an exocrine and an endocrine function)
• Generally ,three layers covered the testis which is tunica vaginalis, tunica albuginea, and tunica vasculosa.
• Tunica vaginalis is a sac of the peritoneum, it surrounds the testis but incompletely, which means It surrounds it on every
side (medially, laterally, and anteriorly, but not posteriorly)
• Under the tunica vaginalis lies the thick fibrous capsule (tunica albuginea)
• The tunica vasculosa is the inner vascular layer of the tunica albuginea
• In the posterior margin of the testis ,the tunica albuginea forms the mediastinum of the testis ,Connective tissue septae
originate from the mediastinum, it passes into the interior of the testis, and it divides the parenchyma of the testis in about
370 conical lobules.
• Each lobule contains sparse connective tissue with endocrine interstitial cells (or Leydig cells) secreting testosterone,
convoluted seminiferous tubules (exocrine) in which sperm production occurs.
Interstitial Tissue
• The interstitial tissue of the testis between the
seminiferous tubules consists of (Leydig cells) in
sparse connective tissue and fibroblasts,
lymphatics, and blood vessels including
fenestrated capillaries
• These cells produce the steroid hormone
testosterone, which is responsible for stimulating
and developing male genital organs and regulating
the process of sperm production and the
emergence of secondary sexual characteristics.
Seminiferous Tubules
• Germinal epithelium and lamina propria are the main components of the seminiferous tubule
• Sperm are produced in the seminiferous tubules .
• Each tubule is actually a loop linked by a very short, narrower segment, the straight tubule, to the
rete testis .
• Each seminiferous tubule is lined
with a complex, specialized
stratified epithelium called
germinal or spermatogenic
epithelium
• The basement membrane of this
epithelium is covered by fibrous
connective tissue, with an
innermost layer containing
flattened, smooth muscle like
myoid cells which allow weak
contractions of the tubule
• The germinal epithelium consists of
two types of cells
1- Large nondividing Sertoli cells,
which physically and metabolically
support developing sperm cells
• 2- Dividing cells of the
spermatogenic cells namely
(spermatogonia, primary and
secondary spermatocytes, and
spermatids ).
They are located within the
invaginations of Sertoli cells.
Testis (cat). (1) Efferent ducts
invested by connective tissue.
(2) Tunica albuginea. (3) Rete
testis. (4) Mediastinum testis.
(5) Seminiferous tubules. H &
E. ×20.
Testis (bull). The seminiferous
tubules are lined by a multilayered
epithelium.
(1) Spermatogonia.
(2) Primary spermatocytes
(3) Spermatids.
(4) Developing spermatozoa.
(5) Interstitial tissue separates the
tubules. H & E. ×160.
Spermatogenesis
Stem cells called spermatogonia
undergo mitosis and give rise to
primary spermatocytes, which
undergo a first meiotic division to
form haploid secondary
spermatocytes
After a very short interval,
secondary spermatocytes undergo
the second meiotic division to
produce small, round spermatids,
which differentiate while still
associated with Sertoli cells.
Spermiogenesis
• Spermiogenesis, is the final phase of sperm production, is the temperature-sensitive process by which
spermatids differentiate into spermatozoa
• These involve flattening of the nucleus, formation of an acrosome that resembles a large lysosome, growth of a
flagellum (tail), reorganization of the mitochondria in the midpiece region, and the loss of much of the
cytoplasm
Spermatogenesis of
anamniotes
• For anamniotes, spermatogenesis occurs in
spermatocysts (cysts) which for most species
develop within seminiferous lobules.
• Cysts are produced when a Sertoli cell becomes
associated with a primary spermatogonium.
• Mitotic divisions of the primary spermatogonium
produce a cohort of secondary spermatogonia
that are enclosed by the Sertoli cell which forms
the wall of the cyst.
• With spermatogenic progression, spermatozoa
is produced which are released, by rupture of
the cyst, into the lumen of the seminiferous
lobule.
Photomicrograph of a semithin section of the testis of a
frog.
There are several cysts of developing sperm in this
photograph.
All of the ells in a cyst are at the same stage of
development, 63 x.
• Photomicrographs of sperm smears
of various vertebrates showing the
characteristic head shape associated
with each species.
• 1- Frog: crescent-like sperm head
and a thin tail
• 2-Turtle:narrow pointed head that
is curved
• 3-Chicken : the heads of chicken
sperm are spindle-shaped and
almost difficult to distinguish from
the midpiece
• 4- Rabbit :A clear head with a
thin tail
INTRATESTICULAR DUCTS
• The intratesticular ducts are the straight tubules,
the rete testis, and the efferent ductules
• All of which carry spermatozoa and liquid from the
seminiferous tubules to the duct of the epididymis
• From the seminiferous tubules, sperm enter
the short straight tubules that lead to channels
of the rete testis in the mediastinum testis,
then move via 15 or 20 efferent ductules
• Rete testis has a simple squamous E
• The efferent ductules are lined pseudostratified
epithelium, and some of the cells are ciliated
• A thin layer of circularly oriented smooth
muscle cells in the walls of efferent ductules
aids sperm movement into the duct of the
epididymis
EXCRETORY GENITAL DUCTS
• EXCRETORY GENITAL DUCTS are (Epididymis, The ductus (or
vas) deferens and The urethra)
• They transport sperm from the Testis to the penis during
ejaculation
• 1-Epididymis : Its long, coiled duct, surrounded by connective
tissue
• it includes a head region where the efferent ductules enter, a
body, and a tail opening into the ductus deferens.
• The epididymal duct is lined with pseudostratified columnar
epithelium with characteristic long stereocilia.
• The duct epithelium is surrounded by a few layers of smooth
muscle cells, arranged as inner and outer longitudinal layers as
well as a circular in the tail of the epididymis
• In it ,sperm undergo maturation and short-term storage
• Peristaltic contractions move the sperm along the duct.
• 2- ductus (or vas) deferens
• From the epididymis the ductus (or vas)
deferens, a long straight tube with slightly
folded mucosa that epithelial lining is
pseudostratified with stereocilia and a
relatively small lumen
• The very thick muscularis consists of
longitudinal inner and outer layers and a
middle circular layer.
• The muscles produce strong peristaltic
contractions during ejaculation, which
rapidly move sperm along this duct from
the epididymis.
• 3-Urethra
• The male urethra can be divided into three sections: the
prostatic urethra, the membranous urethra, the spongy
urethra
• The epithelial lining varies from urethelium proximal to
the bladder, to stratified columnar along the greater part
of the urethra, to stratified squamous at the tip of the
penis
• The urethra is the terminal part of the male duct system
and has both a urinary and a reproductive function
• The urethra carries urine from the bladder to outside of
the body + expelling semen
• Simple tubular mucosal glands open into the urethra.
These are numerous in the horse, bull, boar and ram but
sparse in the dog and cat
ACCESSORY GLANDS
( just in mammals)
• The accessory glands of the male
reproductive tract produce secretions that
are mixed with sperm during ejaculation to
produce semen and that are essential for
reproduction.
• The accessory genital glands are the
seminal vesicles (or glands), the prostate
gland, and the bulbourethral glands.
Seminal Vesicles
• The two seminal vesicles consist of highly tortuous
tubes, enclosed by a connective tissue capsule.
• The mucosa of the tube displays a great number of
thin, complex folds that fill much of the lumen
• The folds are lined with simple columnar epithelial
cells rich in secretory granules.
• The lamina propria contains elastic fibers and is
surrounded by smooth muscle with inner circular
and outer longitudinal layers.
• The seminal vesicles are exocrine glands in which
production of their viscid, yellowish secretion
(semen)
• They are absent in carnivores and are true vesicles
in the stallion .
Prostate Gland
• The prostate gland is a dense organ that surrounds the urethra below the bladder.
• Prostate gland is a discrete compound tubular gland with a thick fibromuscular capsule extending into
the gland
• The epithelium is pseudostratified with tall columnar secretory cells
• In the boar and ruminants, the prostate gland consists mostly of a disseminate portion in the form of a
glandular layer in the submucosa of the proximal (prostatic) urethra.
• It is well developed in the stallion and carnivore
• It is absent in the ram and goat
• In the dog the secretion is serous
• in other animals it is seromucous
Bulbourethral Glands
• The paired round bulbourethral glands (or
Cowper glands), are located in the urogenital
diaphragm and empty into the proximal part of
the penile urethra.
• Bulbourethral glands are compound tubular
and mucus secreting.
• A Striated muscle capsule sends fine
trabeculae into the gland
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PENIS
The penis consists of three cylindrical masses
of erectile tissue, plus the penile urethra,
surrounded by skin
Two of the erectile masses—the corpora
cavernosa—are dorsal
The corpora cavernosa are each surrounded
by a dense fibroelastic layer, the tunica
albuginea
One of the erectile mass is corpus
spongiosum surrounds the urethra
Most of the penile urethra is lined with
pseudostratified columnar epithelium.
In end the corpus spongiosum expands,
forming the glans.
In the glans, it becomes stratified squamous
epithelium
Small mucus-secreting urethral glands are
found along the length of the penile urethra.
PENIS
• In carnivores the terminal part of
the corpus cavernosum ossifies to
become the os penis (baculum)
and contributes to the rigidity of
the penis.
• Small keratinized epidermal
spines are present on the glans
penis of the Cat
• In most amniotes the intromittent
organ contains erectile tissue that
renders it turgid when gorged with
blood
• HEMIPENES of lizards and snakes
are paired eversible sacs attached to
the skin adjacent to the cloacal
opening.
• Crocodiles, turtles, and some
birds have a single trough-like
PHALLUS homologous with the
penis of mammals.
References
• https://pubmed.ncbi.nlm.nih.gov/8
605396/
• https://www.jstage.jst.go.jp/article/
hsj2000/19/2/19_2_63/_pdf
• https://pubmed.ncbi.nlm.nih.gov/2
048751/
• http://www.vivo.colostate.edu/hbo
oks/pathphys/reprod/semeneval/m
orph.html
• Comparative Veterinary Histology,
with Clinical Correlates PDF
• Genital Systems PDF