On the microscopic anatomy of the rete testis a scanning electron microscopic and light microscopic study

Insights into differentiation and function of the transition region between the seminiferous tubule and rete testis

Seminiferous tubules physically connect to the rete testis through short segments called the transition region (TR). During fetal development, this specialized junction is considered the initial site where testis cords begin to form and to grow in length well beyond birth and into adulthood and form convoluted tubular cores. Mitotic activity of the Sertoli cell, the somatic cell of the epithelium, ceases before puberty, but modified Sertoli cells in the TR remain immature and capable of proliferation. This review presents what is known about this specialized region of the testis, with an emphasis on the morphological, molecular and physiological features, which support the hypothesis that this short region of epithelial transition serves as a specialized niche for undifferentiated Sertoli cells and spermatogonial stem cells. Also, the region is populated by an elevated number of immune cells, suggesting an important activity in monitoring and responding to any leakage of autoantigens, as sperm enter the rete testis. Several structure/function characteristics of the transition region are discussed and compared across species.

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.