Three-dimensional analysis of the atrophic process of rat seminiferous tubules after estradiol treatment.

Atrophic changes in the basal portion of the seminiferous tubules caused by daily injections of estradiol have been found by scanning electron microscopy disclosed after a digestion technique using collagenase and trypsin. In the control rat, the smooth basal portion of the epithelium was composed of polygonal Sertoli cells and reticularly-arranged ovoidal spermatogonia. After estradiol treatment, there appeared wavy furrows and ridges, and many folded micro-wrinkles in the complicated basal portion of the seminiferous tubules. The wavy furrows and ridges were repeatedly formed and appeared just like a cornice. These structures ran in an orderly manner perpendicular to the longitudinal axis of the tubules. In contrast, many micro-wrinkles ran in parallel to the longitudinal axis. These two structures had a characteristically similar size and orderly arrangement. They are discussed in relation to the mechanism by which the seminiferous tubules shrink by injections of estradiol.