histo - male repro sys

7/31/2019 Histo - Male Repro Sys

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Introduction

The male reproductive system consists of

a pair of testes

numerous excurrent ducts different accessory glands that produce a

variety of secretions


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Testis

A thick connective tissue capsule, the tunica

albuginea, surrounds each testis.

Posteriorly, the tunica albuginea thickens and

extends inward into each testis to form the

mediastinum testis

There is a vascular layer deep to Tunica Albuginea,

that is Tunica vasculosa


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The capsule sends incomplete septa inwards, dividingthe testis into compartments or lobules (250 innumber)

Each lobule contains 1-4 convoluted, seminiferoustubules.

Seminiferous tubule consist of

an outer layer of fibrous connective tissue,

several layers of fibroblasts the inner layer of whichcalled myoid cells,

a well defined basal lamina

multilayered epithelial cells of germ cells and supportingcells.


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Germinal or Seminiferous Epithelium

Seminiferous epithelium consists of layers ofgerminal cells at different stages of spermatogenesis.

The outer cells, next to the basal lamina are termedspermatogonium, are relatively small cells. They

have the ability of proliferation by mitosis. The newly formed cells can follow one of two paths:

Type A spermatogonia: continue as stem cells

Type B spermatogonia: these are progenitor cells that

give rise to Primary spermatocytes


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Primary spermatocytes are large cells. They enter the

first meiotic division, giving rise to smaller daughter

cells, the secondary spermatocytes, which are

located deeper, and difficult to observe because theyundergo the second meiotic division within short

period, to produce spermatids.

Spermatids at early stages of their formation, are

small, rounded cells with dark nuclei, located close to

the lumen.


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Spermiogenesis

The process by which the spermatids are transformed intospermatozoa is termed Spermiogenesis:

Formation of acrosome.

Condensation and elongation of nucleus.

Development of flagellum.

Loss of much of the cytoplasm

Morphological changes;

formation of head , neck, middle piece and the tail


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Sertoli cells

These are tall, columnar cells, with basally located

oval nucleus.

The cytoplasm contains crystalloid inclusions, and

well developed Golgi complex The lateral membranes of adjacent Sertoli cells form

occluding junctions, thus the wall of seminiferous

tubule is subdivided into the basal compartment and

adluminal compartment . The zonulae occludens

establish blood-testis barrier.


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Functions of Sertoli cells

Physical and nutritional support

Phagocytosis

Establish blood-testis barrier

Synthesis of androgen-binding protein Synthesis of mullarian inhibitory factor during

embryonic stages.

Synthesis of inhibin

Secretion of fructose-rich fluid


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Interstitial tissue

The spaces between the seminiferous tubulesare filled with connective tissue, nerves, bloodand lymphatic vessels.

An additional type of cells is more obviousduring puberty, these are interstitial cells ofLeydig. They are spherical or polyhedral inshape and have central nuclei and esinophiliccytoplasm, These cells synthesizetestosterone.


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BloodTestis Barrier


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GENITAL DUCTS


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Genital ducts

Rete testis, lined by cuboidal epithelium

Ductuli efferentes, are lined by epithelium in which a

group of cuboidal non-ciliated, is alternating with a

group of ciliated cells. The cilia beat in the directionof epididymis.

Epididymis: It is lined by pseudostratified columnar

epithelium with basal cells. The epithelium is resting

on basal lamina and surrounded smooth muscle

cells.


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Epididymis


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Ductus (vas) Deferens

It is a straight tube, with thick muscular wall.

The mucosa forms longitudinal folds

It lined by pseudostratified columnar epithelium with

stereocilia The lamina propria is rich in elastic tissue

The muscular layer consists of inner longitudinal,middle circular, and outer longitudinal layers.


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ACCESSORY GLANDS


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Paired seminal vesicles

Paired bulbourethral glands

A single prostate gland


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Seminal Vesicles

These are two highly tortuous tubes.

Located posterior to the bladder and superior to the prostate

gland.

The excretory duct of each seminal vesicle joins the dilated

terminal part of each vas deferens, the ampulla, to form the

ejaculatory ducts.

The ejaculatory ducts enter and continue through the

prostate gland to open into the prostatic urethra

The seminal vesicle has folded mucosa, that is lined with

cuboidal or pseudostratified columnar epithelium. The cells

are rich in secretory granules.


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Prostate

It is a large accessory male genital gland that surrounds theproximal part of prostatic urethra.

It has 3 zones:

central zone

transitional zone peripheral zone.

The cells of the gland are cuboidal or pseudostratifiedcolumnar epithelium.

Most of the prostate gland consists of small, branched

tubuloacinar prostatic glands

There stromal tissue in between the glandular epithelium thatis rich in smooth muscle cells.

The lumens of the glands may contain Prostatic concretions

(corpora amylacea)


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A transitional epithelium lines the lumen of

the crescent-shaped prostatic urethra.

A longitudinal urethral crest of dense

fibromuscular stroma without glands widens

in the prostatic urethra to form a smooth

domelike structure called the colliculus

seminalis.


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Bulbourethral glands (Cowpers glands)

3-5 cm in diameter

Tubuloalveolar

Lined by simple cuboidal or simple columnar

epithelium

Secretion contains galactose


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Penis

The main components of the penis are 3 cylindrical masses oferectile tissue: corpora cavernosa, placed dorsally, and corpusspongiosum, located ventrally.

The penile urethra is within the corpus spongiosum

Most of the penile urethra is lined with pseudostratified

columnar epithelium. The distal end is lined with stratifiedsquamous epithelium

There are mucous-secreting glands (of Littre), that open intothe urethra.

Corpora cavernosa are covered by dense connective tissue,

tunica albugenia. The spaces in the corpus cavernosa, arevenous spaces and line with endothelial cells


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histo - male repro sys

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