Cell types in the pituitary of the medaka, Oryzias latipes.

Abstract

The pituitary gland of the medaka Oryzias latipes consists of three portions: the pars distalis, the pars intermedia and the neurohypophysis. The pars distalis is further divisible into rostral and proximal zones. On the basis of differences in tinctorial and histochemical properties, eight different cell types are distinguished. The rostral pars distalis contains two types of acidophils: one is clearly revealed by acid violet (Type 1, probably cells producing prolactin-like hormone) and the other type is distinguished by lead haematoxylin (Type 2, probably corticotropic cells). The proximal pars distalis contains two types of basophils, probably gonadotropic cells (Type 3) and thyrotropic cells (Type 4), which distinguished from each other by the differences in avidity for dyes, size and location. Further, the proximal pars distalis contains orange G-positive acidophils (Type 5, probably somatotropic cells) and relatively many chromophobes (Type 6). The pars intermedia contains acidophils (Type 7) and basophils (Type 8); the former is lead haematoxylin-and Gomori-positive and the latter is aniline blue-and PAS-positive. The neurohypophysis is roughly divisible into a rostral portion containing mostly Gomori-negative fibers and a caudal portion containing mostly Gomori-positive fibers.