The ultrastructure of stellate cells in the pars distalis of the salamander pituitary gland

The ultrastructure of a distinct cell type, termed the stellate cell, in the pars distalis of the salamander (Triturus [Notophthalus, Diemyctylus] viridescens viridescens) pituitary gland is described. The cell has three primary characteristics which distinguish it from other cell types of the pars distalis: (1) a lack or sparsity of specific secretory granules, (2) several cellular processes which are long and sheet‐like and (3) cell body and nucleus which are considerably smaller than the cell bodies and nuclei of the chromophilic cells. The stellate cell often has an angular shaped nucleus, and the cytoplasm is characterized by an abundance of glycogen particles, several lipid droplets, an inconspicuous Golgi complex showing no evidence of forming secretory granules, filaments, microtubules and a sparsity of rough endoplasmic reticulum. The cells occasionally contain unusual mitochondria which exhibit longitudinally oriented cristae. From the electron micrographic evidence obtained in this study, it was suggested that stellate cells probably contact all secretory cells in the pars distalis; thus they are favorably situated to play a sustentacular role in the piuitary gland. In addition, the processes of the stellate cell frequently terminate on the outer basal lamina of the pericapillary space. Consideration was given also to a possible secretory role for the stellate cells, but little morphological evidence was obtained to suggest such a function. It was noted, however, that the cells occasionally contain dense bodies about 250 mμ in diameter which were interpreted as possible secretory granules.