Effects of immunization with Freund's complete adjuvant and isologous spermatozoa on the seminiferous epithelium and blood-testis barrier in guinea pigs.

In order to gain insight into the earliest pathological changes underlying the development of autoimmune aspermatogenic orchitis (AIAO) the blood-testis barrier was studied by light and electron microscopy, freeze-etching, and cytochemical techniques early (from 1 to 8 days after adjuvant treatment of isoimmunization). At later times (16 to 21 days) the study was carried out by light microscopy only. Adult male guinea pigs were used either as controls or immunized with Freund's complete adjuvant alone or together with pertussis vaccine. An additional group comprised animals immunized with a suspension of isologous spermatozoa emulsified in Freund's complete adjuvant and with pertussis vaccine. Ultrastructural studies of the testes of experimental animals showed, at earlier periods, apparently normal Sertoli junctions. However, in the adluminal compartment, distended gaps were seen between the facing membranes of adjacent Sertoli cells. At later periods, a massive destruction of the germinal cells were observed. In freeze-fracture replicas, the Sertoli junctions of testes belonging to all the experimental groups were characterized by an irregular network of occasionally interrupted strands of particles associated with the P face (PF). Large concavities determined distensions between interconnecting ridges. The gap junctions were increased in number and in surface. Tracer studies using horseradish peroxidase showed that the marker permeated the myoid cells of a greater proportion of tubules than in control animals. Within the seminiferous epithelium there was only a limited passage of the marker towards the lumina of the tubules. Yet the tracer was always excluded from the adluminal compartment by the Sertoli tight junctions. Our observations suggest the possibility that the FCA causes a loosening of the Sertoli junctions. This condition could enhance exchanges between two antigenically different cellular compartments and, thus, favor occurrence of an autoimmune reaction when cytotoxic factors are experimentally induced, as in iso- or autoimmunization.