The blood-testis barrier in sterile blue fox - silver fox hybrids compared with that in normal foxes of both species.

The integrity of the blood-testis barrier in the blue fox, the silver fox and hybrids of these 2 species was compared at the ultrastructural level during the breeding season by use of a lanthanum penetration technique. In the normal blue and silver fox, penetration of the tracer was blocked at the level of the inter-Sertoli cell junctions, whereas these junctions were permeable in the hybrids, permitting penetration of lanthanum into the adluminal compartment of the seminiferous epithelium. Spermatogenesis in the hybrids was found to be arrested at the early pachytene stage of meiotic prophase. The observed permeability of the inter-Sertoli cell contacts in the hybrids indicates a lack of occluding junctions, and this may be partly the cause of the sterility in these animals.