HISTOCHEMICAL LOCALIZATION OF SOME α-MELANOCYTE STIMULATING HORMONE AMINO ACID CONSTITUENTS IN THE PARS INTERMEDIA OF THE TOAD PITUITARY

Abstract

Within the cells of the pars intermedia of the toad Bufo arenarum Hensel pituitary there exist colloid-like vesicles, as in other anuran. These vesicles showed a positive reaction for tyrosine, tryptophan, arginine, cystine, 1, 2-glycols groups and lipids. The mentioned amino acids have been described as constituents of the polypeptide with alfa-MSH activity, therefore it was assumed by us that the above mentioned positive reactions could be interpreted as histochemical evidences in order to support previous investigations which tend to demonstrate that the colloid vesicles can be interpreted as morphological evidence of melanocyte-stimulating hormone. Because of neither 1, 2-glycols groups nor lipids have been described in the MSH molecule, we think that these positive reactions can be ascribed to a glycolipoprotein which would behave as a carrier substance.