Adrenal histochemistry of some freshwater and marine teleosts

Abstract

The adrenal histochemistry of seven freshwater and six marine species of teleosts was studied and correlated with thyroidal and gonadal activity. The adrenal tissue of each of the 92 fish utilized was subjected to each of the following histochemical reactions: lipids (Sudan black B), phospholipids, cholesterol, ascorbic acid, chromaffin reaction, iodate reaction, and appropriate controls. Adrenal, thyroid and gonadal tissues also were fixed in alcoholic Bouin's fluid and stained with hematoxylin and eosin or PAS (thyroid). The adrenocortical tissue of all species were positive for all the components normally reported in the vertebrate adrenal cortex. However, the marine and sexually mature freshwater species yielded more intense reactions. This was correlated with greater thyroid activity and is considered an indication of a more active secretory state. The possible effects of gonadal activity are discussed. Further, the significance of the marked histochemical variation at the cell level within an individual is also discussed. The chromaffin cells of all species except one yielded positive results with the chromaffin reactions and the iodate reaction. It was not possible to differentiate epinephrine- from norepinephrine-secreting cells because of the considerable interspecific variation in response and the scattered nature of the chromaffin cells.