Male genital system

Dr.Iman Nabil
Sperm make a journey to meet
an egg
 Male genital system
I- External genital organs:
1. Penis.
2. Scrotum
II- Internal genital organs:
1- Primary sex organs: Testes.
2- Male genital ducts:
 Epididymis.
 Vas deferens.
 Ejaculatory ducts.
3- Male genital glands:
 Seminal vesicles.
 Prostate.
 Bulbourethral glands.
Testis
 Testis
• They are two in number, present outside
the body in a cutaneous bag called the
scrotum.
 Covering of the testis
1) Tunica vaginalis: a double layered serous sac of
peritoneum that descent with the testis into the
scrotum.
2) Tunica albuginea:
• A thick connective tissue capsule.
• It is thickened at the back to form the mediastinum
testis, through which the blood vessels enter and vasa
efferentia leave the testis.
• Thin fibrous septa radiate from the mediastinum to
divide the testis into 250 incomplete lobules. Each
lobule contains 1-4 seminiferous tubules.
3) Tunica vasculosa: a highly vascular loose connective
tissue that extends in between the seminiferous
tubules.
 The seminiferous tubules
• They are the structural and functional
units of the testis.
• It is the exocrine portion that produces
sperm.
• Each one is a coiled loop, terminating as
the tubuli recti.
 The seminiferous tubules
• They are circular with basal lamina&
narrow lumen.
• Each tubule is surrounded by peritubular
myoid cells and fibroblasts forming the
tunica propria.
• In between the tubules: the tunica
vasculosa contains interstitial Leydig cells.
 Lining cells of the seminiferous
tubules
I- Spermatogenic cells:
• The main cell population.
• They are the male germ cells arranged in
successive layers from the basal lamina to
the lumen of the ST.
II- Sertoli cells.
Spermatogenic cells
 46 S chromosomes

46 S chromosomes 46 d chromosomes

46 S chromosomes
 Meiosis I Meiosis II

46 d chromosomes

23 d chromosomes

23s chromosomes
 1- Spermatogonia
• Origin: they are the stem cells.
• Structure:
Shape: small, round cells& resting on the basal lamina.
Nucleus: contains the diploid number of chromosomes
(46 s).
In sexually immature testis: they are the only type of
spermatogenic cells present in the seminiferous
tubules forming 4-8 rows.
In sexually maturation: forming 1-2 layers.
• Fate: divide by mitosis to maintain their number& give
rise to primary spermatocytes.
 2- Primary spermatocytes
• Origin: at puberty, arise from mitotic division of
spermatogonia.
• Structure:
Shape: largest spermatogenic cells, found in 2-3
layers next to spermatogonia. They are frequently
seen in sections as the prophase of first meiotic
division lasts for 22 days.
Nucleus: large, pale & contains the diploid
number of chromosomes (46 d-chromosomes).
• Fate: enter the first meiotic division to give rise to
secondary spermatocytes.
 3- Secondary spermatocytes
• Origin: from the first meiotic division of
primary spermatocytes.
• Structure:
Shape: smaller than primary spermatocytes,
but rarely seen in sections as they quickly
enter the second meiotic division.
Nucleus: contains the haploid number of
chromosomes (23 d-chromosomes).
• Fate: enter the second meiotic division to
give rise to spermatids.
 4-Spermatids
• Origin: from second meiotic division of the secondary
spermatocytes.
• Structure:
Shape: 2 successive stages of maturation:
1- Early spermatids: small, round with a central round
nucleus.
2- Late spermatids: elongated with a dark nucleus&
attached to the apices of Sertoli cells.
Nucleus: contains the haploid number of chromosomes
(23 s-chromosomes).
• Fate: do not divide, they undergo morphological changes
to be transformed into spermatozoa.
 5-Spermatozoa
• Origin: differentiated from the late
spermatids.
• Structure: they fill the lumen of
seminiferous tubules and attach to the
apices of Sertoli cells.
 1- Spermatogonium 2- Primary spermatocyte 3- Secondary spermatocyte 4- Spermatid

1- Origin They are the stem cells. From mitotic division of From the first meiotic From second meiotic
spermatogonia. division of primary division of the
spermatocytes. secondary
spermatocytes.

2- Shape small,rounded & resting on Largest spermatogenic Smaller. Early: small,rounded.

basal lamina cells. with a central round
-Sexual immature testis: 4-8 -arranged in 2- 3 layers. Rarely seen in section .nucleus
layers. -Frequently seen in Late: elongated with
-Sexual maturation:1-2 section dark nucleus
layers.

3- nucleus .contain 46 S chromosomes large,pale, contains 46-d .Contains 23 d chromosomes contains 23 S

.chromosomes .chromosomes

4- Fate Enter mitosis to maintain its Enter first meiotic Enter second meiotic division Don’t divide, but
number& give rise to division to give rise to to give rise to spermatids. undergoes
primary spermatocytes secondary morphological changes
spermatocytes into spermatozoa.
 Spermatogenesis
The process of transformation of the germ cell into a spermatozoa inside seminiferous tubules,
which begins at puberty and continues throughout the life.

I-Spermatocytogensis:
Successive mitotic & meiotic divisions of I
spermatogenic cells to give spermatids.

II-Spermiogensis:
Morphological changes of spermatids
to be a spermatozoa.
II
 Spermiogensis
• Morphological changes of spermatids into spermatozoa.
• Occurs while spermatids attached into Sertoli cell apices.
 Spermiogensis

1- Golgi phase:
• Acrosomal granules ( hydrolytic enzymes)
formed inside Golgi of spermatid.
• Fusion of these granules to form a single
acrosomal vesicle near nucleus.
• The two centrioles migrate to the caudal
pole of the nucleus.
• One of centriole forming axoneme of the
flagellum.
 Spermiogensis
2- Cap phase:
• The acrosomal vesicle spread to covers the
anterior ½ of the condensed nucleus.
 Spermiogensis
3- Acrosome phase:
• The nucleus becomes more elongated &
condensed.
• The cytoplasm displaced caudally.
Mature spermatozoa

9 outer

Circumferential ribs

columns
 Spermiogensis
4- Maturation phase:
• Shedding of the excess cytoplasm (residual
bodies) & phagocytosed by Sertoli cells.
• Spermiation: Release of mature sperm into
lumen of ST.
Mature spermatozoa
 Structure of mature
spermatozoa
It is formed of head, neck and tail and surrounded by the cell membrane:
1- Head:
 Have a dense nucleus, containing 23 s chromosomes.
 covered with acrosome.
2- Neck (connecting piece): contains the centrioles.
3- Tail ( flagellum): divided into:
 Middle piece: extends from the neck to the annulus. It contains:
A- The axoneme.
B- 9 outer dense fibers.
C- Mitochondrial sheath: a spirally arranged to provide energy for motility of tail.
 Principal piece: extends from the annulus to the end piece. It contains:
A- The axoneme.
B- 7 outer dense fibers.
C- The fibrous sheath.
 End piece: consists of the axoneme covered by the cell membrane.
Test your self???
 Immotile cilia syndrome
• Lack of dynein arms results in immotile sperms
& male infertility.
 Acrosomal reaction
• A reaction occurs in the mature sperm in which the acrosomal membrane fuses
with the sperm membrane to creates pores through which the hydrolytic
enzymes of the acrosomal cap escape to digest the protective coverings of the
ovum during fertilization.
 Sertoli cells
• They are the non proliferating, non spermatogenic
cells of the seminiferous epithelium.
• Site: in between spermatogenic cells, extending
from the basal lamina to the lumen of the
seminiferous tubules.
• Shape: tall, irregular pyramidal cells.
• Nucleus: large, euchromatic lying in the broad
basal part of the cell. It has deep infoldings; with
a tripartite nucleolus.
• Cytoplasm: pale due to the presence of
numerous lipid droplets.
 How does the Sertoli cell adapt to
its functions?
• EM:
1-Lateral boundaries: not well seen (recesses)
protection, support & nutrition.
2- sER around lipid droplets ???.
3-Well developed Golgi &elongated
mitochondria synthesis of inhibin,
androgen binding protein, luminal fluid&
mullarian inhibiting substance.
5- Lysosomes phagocytosis of residual
cytoplasm& dead sperms.
6- Microtubules & microfilaments
structural support & spermiation.
 7-Blood testis barrier
Definition: Occluding junctions between
adjacent Sertoli cells above the level of
spermatogonia.
Functions:
1- Prevent autoimmune reaction against
developing spermatogenic cells.
2- Protect the microenvironment of the ST.
 7-Blood testis barrier
• It divides the seminiferous epithelium into two
separated compartments:
A- Basal compartment: contain
1- Fibroblasts, myoid cells and blood vessels in
tunica vasculosa.
2- Basal lamina.
3- Spermatogonia.
B- Adluminal compartment: contain
2- 1ry, 2ry spermatocytes.
2- Spermatids.
3- Sperms.
 Interstitial cell of Leydig
• Origin: from undifferentiated mesenchymal
cells of testis.
• Function: secrete the testosterone.
• Site: in tunica vasculosa, in between the
seminiferous tubules, surrounded by
fenestrated capillaries.
• Structure: Steroid secreting cells
LM: large, polyhedral cells with large nuclei
and eosinophilic vacuolated cytoplasm.
EM: sER, mitochondria with tubular cristae&
numerous lipid droplets.
Which statement is the best to
describe the pointed cell by the
red arrow?
1- They are frequently seen in histological
sections.
2- They are present at birth.
3- They contain the haploid number of the
chromosomes.
4- They can not divide any more.
Which statement is the best to
describe the pointed cell by the
red arrow?
1- They are frequently seen in histological
sections.
2- They are present at birth.
3- They contain the haploid number of the
chromosomes.
4- They can not divide any more.