Histopathology of the cryptorchid testis.

Morphologic studies of cryptorchid testes do not show any pathologic changes other than one of malpositioning within the first year of life. Beginning with the third year of life histologic alterations become apparent in all structures. There is a marked increase in the number of mitochondria, which later degenerate and develop vacuoles. The endoplasmic reticulum loses its ribosomes almost completely. An enlargement of the perinuclear space develops between the lamellae of the nuclear membrane in the Sertoli cells and the spermatogonia. Light microscopy reveals a decrease in the number of spermatogonia and lack of development of the seminiferous tubules. The tunica propria is widened by a growing number of collagenous fibers, which become arranged in bundles.