Restoration of involuted zymogenic cells in hypophysectomized rats by replacement therapy.

Following hypophysectomy of the rat, partial involution occurs in the zymogenic cells of the stomach (Baker and Abrams, '54), parotid gland (Baker and Abrams, '55), pancreas (Baker and Pliske, '57) , submandibular gland (Lacassagne and Chamorro, '40 ; Grad and Leblond, '49) , and in the intestinal cells of Paneth (Baker, Kent and Pliske, in press). Insofar as they have been studied, enzyme synthesis is suppressed in these cells, also. The question of how the hypophysis exerts its influence over zymogenic cells will be answered only when they are restored to normal in hypophysectomized rats by replacement therapy. The purpose of this report is to present the results of experiments in which somatotropin, corticosterone and thyroxine were administered in combination. These hormones were selected for several reasoiis. Somatotropin has induced a significant but limited increase in weight of the pancreas in hypophysectomized rats (Kinash et al., '53; Baker and Abrams, '55). The absolute weight of the parotid gland was increased, also, by somatotropin in hypophysectomized rats, although not out of proportion to the augmented body weight (Baker and Abrams, '55). Thyroxine was used be-