BLOOD TESTES BARRIER

blood-testis barrier:

blood-testis barrier The blood-testis barrier (BTB) is a physical barrier between the blood or lymph vessels and the lumen of seminiferous tubules of the animal testes.

HOW IT FORM:

HOW IT FORM Myoid layer Sertoli cell junction Sertoli cell junction formed by tight connections between the Sertoli cells, which are sustentacular cells (nurse cells) of the seminiferous tubules, and nourish the spermatogonia.

Histology of seminiferous tubule :

Histology of seminiferous tubule

Slide 5:

Germinal epithelium of the testicle. 1 basal lamina, 2 spermatogonia, 3 spermatocyte 1st order, 4 spermatocyte 2nd order, 5 spermatid, 6 mature spermatid, 7 Sertoli cell, 8 tight junction (blood testis barrier)

Slide 6:

1 - seminiferous tubule 2 - spermatogonia 3 - primary spermatocytes 4 - secondary spermatocytes 5 – spermatids 6 - interstitial connective tissue 7- Leydig cells Histology of seminiferous tubule

FUNCTION:

FUNCTION Sertoli cell’s tight junctions make up the blood-testis barrier divide the basal compartment and an adluminal compartment. Spermatogonia are located outside the barrier (they are genetically identical to the somatic cells) and can respond to various factors. During sperm development new genetic combinations appeared a result of crossingover.

FUNCTION CONT…:

FUNCTION CONT… Since sexual maturity occurs long after the development of immunocompetence, the differentiating sperm cells can be recognized as ‘foreign’ and provoke an immune response that will destroy the sperms. Protects the developing sperms. Large molecules (immunoglobulins) cannot penetrate.

FUNCTION cont… :

FUNCTION cont… Protects highly immunogenic material from leaking out causing autoimmune destruction of the testes It is permeable to testosterone Retain ABP, inhibin, and enzyme inhibitors within the luminal compartment. Selectively secreted K + into adluminal space ( make sperm quiescent )

BTB Destroyers:

BTB Destroyers Anything that destroys the BTB will lead to an impairment of meiosis and spermatogenesis. BTB Destroyers include: Heat Heavy Metals Pesticides Low amounts of FSH and/or Testosterone

BTB can be damaged by:

BTB can be damaged by Trauma to the testes Torsion Impact Surgery Vasectomy .

If BTB damage:

If BTB damage Impairment of spermatogenesis Leakage of spermatozoa into interstitial space leading to severe inflammation Immunoglobulins inter into lumen of seminiferous tubule to cause inflammation of the testis