Combined stain for fish pituitary.

A new combined stain is described for the study of cell types in the fish pituitary. Tissues are prepared by fixing in formol-sublimate and then embedded in paraffin wax. Tissue is sectioned at 5 micron and than stained sequentially with performic acid-alcian blue, periodic acid-Schiff, orange G, and acid fuchsin. As a result of this procedure acidophils stain as follows: lactotropes, red; corticotropes, light pink; melanotropes, bright pink; and somatotropes, orange. Cyanophils stain either magenta red (gonadotropes) or blue (thyrotropes). Neurosecretory material and the fibers of the pars nervosa which penetrate the pars intermedia stain light blue.