Histological and histochemical changes of organs associated with adjustment to the environment

Abstract

Endocrine organs change in structure and function during adaptation to water of different salinities. In eels the pituitary-adrenocortical axis is most active in animals adapted to seawater for 4 weeks. These changes are more pronounced in yellow eels. Prolactin-producing cells are stimulated in freshwater animals. The reactions of the corpuscles of Stannius of yellow eels differ significantly from those of silver eels. There is some evidence that the hypothalamoneurohypophyseal system is less active in seawater and is stimulated in distilled-water eels. In Gobius paganellus, transfer to freshwater results in stimulation of the adrenals. Adaptation of larval and adult Xenopus to 1.3% salt water activates the adrenocortex. Transfer to distilled water has no uniform effects.