male reproductive system department of histology and embryology medical college in three gorges...

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