The Pituitary Gland of the Sockeye (Oncorhynchus nerka) During Sexual Maturation and Spawning

Abstract

This communication presents the results of a study of the pituitaries of 150 sockeye salmon in various stages of sexual maturation from the time they entered freshwater till after completion of spawning. In the homologue of the adenohypophysis, 9 different cell types were distinguished. On the basis of changes in tinctorial and histochemical properties and relative proportions of each of these cells, it was concluded that the sockeye pituitary contains 6 different hormone producing cell types. One of these probably possesses a gonado-trophic function. Degenerative phenomena in the pituitary were found in the sexually ripe and the spent salmon, but only to a limited extent. The implications of the changes in the occurrence of the 6 different cell types and the degenerative alterations are discussed in relation to gonad development and the death after spawning.