Morphology of the rat rete testis in experimental autoimmune orchitis

The role of the rete testis and related structures in the development of experimental autoimmune orchitis (EAO) was studied in adult inbred Sprague-Dawley rats. Histology and electron microscopy showed focal perivascular infiltration and an increase in the number of mast cells and polymorphonuclears. Often there were vacuolated macrophages. These changes were first observed two weeks after the beginning of immunization, but they did not clearly precede lesions in seminiferous tubules. Increased amounts of cellular debris appeared in rete cavities, suggesting damage to germinal epithelium. Lanthanum tracer studies of immunized rats showed local lesions in the blood-testis barrier of the seminiferous tubules but did not indicate spreading of lesions from the rete testis. Efferent duct ligation of immunized rats for 24 h did not increase the frequency of lesions. The present observation do not support the theory that the rete testis is the route of spreading of EAO.