Histology:2Nd Stage Dr. Raja Ali

Histology:2Nd Stage Dr. Raja Ali

Histology:2nd stage Dr. Raja Ali

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The Male Reproductive System II

Sertoli Cells (fig.1):

 The Sertoli cells, are highly important For the function of the testes.

 They are columnar or pyramidal cells that largely envelop cells of the spermatogenic lineage and function as supporting cells or nurse cells.

 The bases of the Serroli cells adhere to the basal lamina and their apical ends extended to the lumen of the sem. tubules.

 Smooth ER, some rough ER, well-developed Golgi complexes, as well as numerous mitochondria and lysosomes. Have elongated nucleus, which can be triangular in outline.

 As , flagellar tails of the spermatids develop, they appear as tufts extending from the apical ends of the Sertoli cells .

Sertoli cells have several specific functions within the sem. tubules epithelium:

A-Support, protection , and nutrition of developing spermatogenic cells.

B-Exocrine and endocrine secretion:

  • Sertoli cells continuously secrete into the seminiferous tubules a fluid used for sperm transport in the direction of the genital ducts.
  • Secretion of nutrients and androgen-binding protein (ABP), which concentrates testosterone to a level required for spermiogenesis, is promoted by follicle-stimulating hormone (FSH).
  • In an endocrine manner, Sertoli cells release the steroid estradiol derived from testosterone and secrete the inhibin , which in a feedback loop with the anterior pituitary gland suppresses synthesis and .
  • In the fetus Sertoli secrete a müllerian-inhibiting substance (MIS) that causes regression of the embryonic miillerian (paramesonephric) ducts; without MIS these ducts persist and become parts of the female reproductive tract.

C-Phagocytosis: During spermatogenesis excess cytoplasm shed as residual bodies is phagocytosed and digested by Sertoli cells lysosomes.


Fig.(1): Sertoli cells

Interstitial Tissue: fig.(2)

The spaces between the seminiferous tubules are filled with connective tissue, the site of androgen production.

Contains mast cells,macrophage,nerves, lymphatics &blood vessels.

During puberty ,interstitial or Ladig cells appear, produce the male hormone testosterone ,this hormone responsible for the development of the secondary male sex characteristics.

Testosterone secretion by interstitial cells is promoted by the luteinizing hormone (LH),which is also called interstitial cell stimulating hormone (ICSH).

Fig.(2): Seminiferous tubule and interstitial cells. Contive tissue( CT), myoidc ells( M),interstitial cells (IC),fibroblast (F),Sertoli cell (SC), spermatogonia (SG), Pimary spermatocytes (PS), Seminiferous tubules (ST).

Intratesticular Ducts:

  • The Intratesticular genital ducts are : the straight tubules (tubuli recti), the reti testis, and the efferent ductules (fig. 3). These ducts carry spermatozoa and liquid from the sem. tubules to the duct of the epididymis .
  • The straight tubules recognized by the gradual loss of spermatogenic cells,and their walls are lined only by Sertoli cells.

Fig.(3): Intratesticular Ducts

  • All the straight tubules empty into the rete testis, an interconnected network of channels lined with cuboidal epithelium. The channels of the rere testis are embedded within the connective tissue of the mediastinum.
  • The reti testis are lined by an usual epithelium with groups of nonciliated cuboidal cells altering with groups of tallar ciliated cells .

The efferent ductules are lined by a simple epithelium with a characteristic scalloped appearance in section, consisting of patches of cuboidal cells with water-absorbing micro villi alternating with patches of taller cells with cilia .This epithelium creates a fluid flow that, together with contractile activity of the thin muscularis around the efferent ductules, carries sperm toward the epididymis.

Excretory Genital Ducts:

Excretory genital ducts are those of the epididymis , the ductus (vas) deferens, and the urethra. They transport sperm from the epididymis to the penis during ejaculation (janqueira).

A- The duct of the epididymis

 The duct of the epididymis is a single highly coiled tube. Together with a connective tissue capsule and blood vessels this long duct forms the head, body, and tail of the epididymis, lies along the superior and posterior sides of each testis .

 Sperm are stored in the epididymis and attain there various final characteristics including:

  • motility .
  • membrane receptors for zona pellucida proteins.
  • maturation of the acrosome, and ability to fertilize.

The efferent ductules join the duct in the head of the epididymis and it opens into the ductus (vas) deferens at the tail.

The epididymal duct is lined with pseudostratified columnar epithelium cells with long, branched, irregular microvilli called stereocilia. (janqueira).

B- The ductus (vas) deferens:

  • From the epididymis , a long straight tube with a thick, muscular wall, continues toward the prostatic urethra and empties into it.
  • It is characterized by a narrow lumen and a thick layer of smooth muscle .
  • Its mucosa is folded longitudinally and is lined along most of its length by pseudostratified columnar epithelium with sparse stereocilia.
  • The lamina propria is rich in elastic fibers and the very thick muscularis consists of longitudinal inner and outer layers and a middle circular layer. The ductus deferens forms part of the spermatic cord, which includes the testicular artery, the pampiniform plexus, and nerves .
  • After passing over the urinary bladder, the ductus deferens dilates to form an ampulla (janqueira ).
  • At the final portion of the ampulla, the seminal vesicles join the duct. From there on, the ductus deferens enters the prostate gland and opens into the prostatic urethra.
  • The segment entering the prostate is called the ejaculatory duct.
  • The mucosa of the ductus deferens continues through the ejaculatory duct, but the muscle layers disappear beyond the ampulla.

Accessory Glands:

The accessory glands of the male reproductive tract produce secretions that are added to sperm during ejaculation to produce semen.

The accessory genital glands are the seminal vesicles, the prostate gland, and the bulbourethral glands (janqueira).

A-The seminal vesicles:

The two seminal vesicles consist of tortuous tubes.

The unusual mucosa displays a great number of thin, complex folds that fill most of the lumen (Figure 21-14).

Are lined with simple or pseudostratified columnar epithelial cells rich in secretory granules.

The seminal vesicles are exocrine glands that produce a viscid, yellowish secretion containing fructose , citrate, inositol, prostaglandins, fibrinogen, their shape and activity are dependent on adequate levels of testesteronn.

B-The prosrate gland:

  • The prosrate gland is a dense organ surrounding the urethra bellow the bladder.
  • The prosrate is a collection of branched tubuloalveolar glands, surrounding by a dense fibro-muscular stroma covered by capsule.
  • The glands are arranged in concentric layers around the urethra:

 The inner layer mucosal glands.

 The intermediate layer of submucosal glands.

 Peripheral layer with the prostateʾs main glands.

  • The prosrate has three zones, corresponding to the glandular layers:

 The transition zone occupies about 5%o of the prostate volume, surrounds the prostatic urethra, and contains the mucosal glands emprying directly into the urerhra.

 The central zone occupies 250/o of the glands volume and contains the submucosal glands with longer ducts.

 The peripheral zone occupies abowT\o/o of the prostate and contains the main glands wich still longer ducts. Glands of this area are the most common location of both inflammation and cancer.

  • The tubuloalveolar glands of the prostate are lined by a simple or pseudostratified columnar epithelium. The glands produce prostatic fluid containing various glycoproteins and enzyme.
  • The prostate is surrounded by a fibroelastic capsule. Septa from this capsule penetrate the gland and divide it into indistinct lobes.
  • As with the seminal vesicle, the structure and function of the prostate depend on the level of testosterone.

Small spherical concretions, are frequently observed in the lumens of the prostatic glands (janqueira) , they are called corpora amylicea, or prostatic concretions .

C-The paired round bulbourethral glands:

  • (Cowpert glands), are located in the urogenital diaphragm (janqueira) and empty into the proximal part of the penile urethra.
  • Each gland has several lobules with tubuloalveolar secretory units lined by a mucus-secreting simple columnar epithelium dependento n testosterone.

Penis:

  • The main components of the penis are three cylindrical masses of erectile tissue, plus the penile urerhra ,surrounded by skin (janqueira).
  • Two of these cylinders-the corpora cavernosa are placed dorsally.
  • The other-the corpus spongiosum-is ventral and surrounds the urethra(janqueira). At its end the corpus spongiosum expands, forming the glans.
  • Most of the penile urethra is lined with pseudostratified columnar epithelium.
  • In the glans, it becomes stratified squamous epithelium continuous with that of the thin epidermis covering the glans.
  • Small mucus-secreting urethra glands( glands of Littre) are found along the length of the penile urethra .
  • The corpora cavernosa and the corpus spongiosum are
  • both composed of erectile tissue,