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Male Reproductive System
Department of Histology and Embryology Medical college in Three Gorges University
• The male reproductive organs
testis
epididymis,
ductus deferens
seminal vesicle, the prostate,
the male urethra, the penis
THE TESTIS
seminiferous tubules Interstitial tissue
seminiferous tubules
efferent ductules
the duct of the epididymis
straight tubules
rete testis
ductus deferens
• General Structure of Seminiferous Tubules
• The wall of each tubule is made up of
(1)an outer layer of fibrous tissue which also
contains muscle like (myoid) cells.
(2) basal lamina
(3) Germ cells and sustentacular cells or the
cells of sertoli.
• Germ cells:
Spermatogonia
Primary spermatocytes
Secondary spermatocytes
Spermatids
Spermatozoon
(1) Spermatogonia:It is the stem cells of spermatogenesis after puberty. It is about 12um in diameter that are rest on the basement membrane.
Type A
Type B
• (2)Primary spermatocytes are formed by
mitotic division of spermatogonia. These
are large cells with large spherical nuclei.
Each primary spermatocyte undergoes
meiosis to give rise to two secondary
spermatocytes This is the first meiotic
division in which the number of
chromosomes is reduced to half.
• (3) Secondary spermatocytes are smaller
than primary spermatocytes, and so are their
nuclei. We have seen that each secondary
spermatocyte has the haploid number of
chromosomes. It divides to form two
spermatids by the second meiotic division.It
rapidly undergoes the second meiotic
division and are therefore seldom seen.
• (4) Spermatid: Each spermatid is a rounded
cell with a spherical nucleus. Both cell and
nucleus are much smaller than in the case of
spermatogonia or spermatocytes. The
spermatids undergoes changes in shape, and
in the orientation of its organelles, to form a
spermatozoon. This process is called
spermiogenesis.
• Structure of a Mature Spermatozoon
• The spermatozoon has a head, a neck, a
middle piece and a principal piece and end
piece or tail. The head is covered by a cap
called the acrosomic cap, anterior nuclear
cap, or galea capitis.
• Sustentacular Cells or Cells of Sertoli
• These are tall, slender cells having an
irregularly pyramidal or columnar shape.
The nucleus lies near the base of the cell. It
is light staining and is of irregular shape.
There is a prominent nucleolus.
• The base of each sustentacular cell rests on the basement membrane, spermatogonia being interposed amongst the sustentacular cells. The apex of the sustentacular cell reaches the lumen of the seminiferous tubule. Numerous spermatids, at various stages of differentiation into spermatozoa, appear to be embedded in the apical part of the cytoplasm.
• Function: Sustentacular cells support
developing germ cells and provide them
with nutrition. They probably secrete fluid
that helps to move spermatozoa along the
seminiferous tubules.
• Sustentacular cells may also act as
macrophages. In the adult testis
sustentacular cells are less prominent than
germ cells. They are more prominent than
germ cells before puberty, and in old age.
• The interstitial tissue:
Apart from interstitial cells, the interstitial
tissue contains collagen fibres, fibroblasts,
macrophages, mast cells, blood vessels and
lymphatics.
Interstitial Cells
• The interstitial cells (of Leydig) are large,
round or polyhedral cells lying in the
connective tissue that intervenes between the
coils of seminiferous tubules. Their nuclei are
eccentric. The cytoplasm stains lightly and
often has a foamy appearance (because of the
removal of lipids during processing of tissues).
• Interstitial cells secrete male sex hormone
(testicular androgens).
• ACCESSORY UROGENITAL ORGANS
• Structurally, the epididymis consists of two
parts. The head is formed by highly
convoluted continuations of the efferent
ductules. these are lined by ciliated
columnar epithelium.
• The body and tail of the epididymis are
made up of the duct of the epididymis,
which is greatly coiled on itself. The duct is
lined by pseudostratified columnar
epithelium in which there are tall columnar
cells, and shorter basal cells that do not
reach the lumen.
• The luminal surface of each columnar cell
bears non-motile projections that resemble
cilia. These stereocilia are seen by EM to be
thick microvilli. The basal cells are
precursors of the tall cells. The tubules of
the epididymis are surrounded by smooth
muscle and by a rich network of capillaries.
• The Ductus Deferens
• The Prostate
concretions