Impermeability of sertoli cell junctions to prolonged exposure to peroxidase

The competence of the occluding junctional complexes between Sertoli cell has been studied after continuous exposure of the testis to a high concentration of peroxidase for periods of 30 minutes to 4 hours. Horseradish peroxidase in buffered saline solution (10 mg/ml) infused through an indwelling polyethelene tube implanted interstitially in the testis becomes widely distributed throughout the organ via the extensive system of lymphatic sinusoids. All the components of the testicular interstitium become heavily infiltrated. A large amount of peroxidase accumulates in the acellular layers of the lamina propria of the seminiferous tubules. Some traverses patent intercellular clefts between myoid cells and enters the interspaces of the basal compartment of the epithelium. The Sertoli cell junctions effectively prevent any further penetration of peroxidase toward the adluminal compartment and in no case was the tracer observed in the tubular lumen. The present study extends previous observations based on brief exposure to tracers and confirms the conclusion that the occluding Sertoli cell junctions are highly impermeable to small tracers and constitute the main structural component of the blood-testis barrier.