Stellate Cells in the Pituitary Gland of the Salamander

Abstract

The fine structure of five cell types in the pars distalis of the salamander [Notophthalmus (Triturus) viridescens viridescens] pituitary gland has been described. Four of these possess characteristic secretory granules (figure 1) and apparently they are involved in the synthesis and secretion of pituitary hormones. The other cell (Cell type #5 or “stellate cell”) does not possess characteristic secretory granules (figures 1 and 2) and they show a morphology which does not suggest a secretory function. The present report extends the observations on the fine structure of the stellate cell and considers, in addition, the distribution of this cell throughout the pars distalis.The stellate cell displays many slender, cytoplasmic extensions which penetrate between the secretory cells (figure 1). These extensions contact processes from other stellate cells and desmosomes are found at the points of contact. Moreover, desmosomes are frequently located between the stellate cells and the secretory cells (figure 2). Thus, the stellate cells are not only linked to each other throughout the pars distalis, but to each secretory cell as well. Stellate cell processes contact the outer basement lamina of the pericapillary space and often such processes follow the contour of the basement lamina for considerable distances. They do not penetrate, however, into the pericapillary space.