Injury of primary spermatocytes during the meiotic prophase and temporary arrest of spermatogenesis induced by fluoracetamide in the rat.

Abstract

Rats were given a single intraperitoneal injection of fluoroacetamide (FAA) and their testes were examined at selected intervals by light and electron microscopy. The sequence of events occurring in the seminiferous tubules is a rapid degeneration of primary spermatocytes in late prophase accompanied by a more gradual failure of secondary spermatocytes and spermatids. Since spermatocytes failed from early prophase to complete prophase, no new population of spermatids developed later. The meiotic prophase at the pachytene stage represents the “Key point” of arrest of spermatogenesis. In the terminal stages of damage all that remained in the seminiferous tubules were spermatogonia and Sertoli cells. It is the differential sensitivity of the germ cells that is responsible for the marked variation in damage observed between 48 und 96 hours after FAA administration. After this time the variation becomes less because a more extreme condition is generally reached. Four months after FAA administration there was a return to normal. Our studies demonstrate that FAA exerts an effective antispermatogenic action which is reversible. With the aid of electron microscopy it has been shown that cytoplasmic changes such as swelling of mitochondria occurred in primary spermatocytes in late prophase before nuclear lesions developed. On the basis of these findings, suggestions are made on the mode of action of fluoroacetamide.