ELECTRON MICROSCOPIC OBSERVATIONS ON THE NORMAL AND DENERVATED ADRENAL MEDULLA OF THE RAT¹

Abstract

Mulon (1905) first observed that adrenal medullary cells when fixed with osmic acid exhibit intracellular osmiophile granules. Assuming these bodies to be comparable with the chromaffin granules of Hultgen and Anderson (1899) and Kohn (1902), he claimed that the osmic acid staining reaction was a specific histochemical test for adrenalin. Bennett (1941) disputed such an absolute specificity on the grounds that, besides adrenaline itself, other reducing substances (many of them polyphenol precursors of adrenaline) were blackened by osmic acid. Since osmic acid has recently proved effective as a tissue fixative for electron microscopic study (Porter, Claude and Fullam 1945: Palade 1952: Dalton 1955), it seemed especially relevant to examine the adrenal medulla by this method. MATERIAL AND METHODS The Normal Medulla. During the electron microscopic study of the rat adrenal cortex (Lever (a) in press) the medulla was concurrently examined in some 25 animals. In addition 12 more normal glands were obtained as controls in the denervation experiments described below.