Tubular hyalinization in human testis.

Tubular hyalinization was studied both light and electron microscopically in 22 cases. 8 of them were found in undescended testes and 5 cases represented possible intermediary forms with only partial hyalinization of the tubules. In these testes spermatogenic arrest, hypospermatogenesis, only Sertoli cells and areas with normal spermatogenesis were found. The only remaining cell type in the tubular wall as well as, in some cases, also within the tubules was the fibroblast. Ultrastructurally the tubules were filled with collagen fibers. Based on these findings it is suggested that tubular hyalinization may be the end stage of a variety of pathologic conditions causing damage to the seminiferous tubules.