Ultrastructural modifications of renal cells in the three-spined stickleback (Gasterosteus aculeatus L.) after castration.

The mechanisms of cellular autophagy have been studied in the renal epithelium of male sticklebacks (Gasterosteus aculeatus L.) following castration. Two main types of alteration are described at the level of the proximal tubule cells. At first, the formation of endoplasmic reticulum whorls is observed, followed immediately by the secretion of lacunar progranules and by nucleolar modifications. These alterations lead to a progressive decrease of the glandular activity of the cells. The other main effect of castration is a general involution of the secretory granules still present in the cells. The involutive processes which lead to the complete destruction of the secretory material and, sometimes, of entire proximal cells, are described. In the collecting tubules, a marked and rapid decrease in glandular activity occurs, followed by disappearance of the mucous secretions. Small dense granules, supposedly lysosomes, are present. The processes described also appear to be characteristic of the normal involution of the renal cells occurring at the end of the breeding period. The findings strongly suggest that the male sex hormone may exert a double control on the renal cells in the stickleback, at both the cytoplasmic and nucleolar levels.