Scanning electron microscopic study on the shape of infertile seminiferous tubules: a hypothesis of pathogenesis of idiopathic male infertility.

The shape of infertile seminiferous tubules was studied on testicular biopsied specimens from patients with idiopathic male infertility using the scanning electron microscope. A parallel study of the same sections was performed by ordinary light microscopy. Normal seminiferous tubules were revealed to be shaped like a weaving cylinder, whereas infertile seminiferous tubules were strangulated in various places, or appeared similar to a tail-like rope which became gradually more slender. These strangulated or slender parts of tubules seemed to correspond to the smaller tubules with thickened tubular walls that were recognized under the light microscope. It is suggested that these thickened tubular walls suppress spermatogenesis by a nutritional disturbance, and the strangulations of infertile tubules interfere with sperm transport by tubular blockage or germinal disorganization and interrupted contractions of the tubules.