SOME OBSERVATIONS ON THE HISTOLOGY AND HISTOCHEMISTRY OF THE CHROMAFFIN CELLS PROBABLY STORING DOPAMINE

The presence of a new type of chromaffin cell in certain tissues in ruminants was reported in previous studies. The results obtained by indirect methods indicated that the cells store dopamine and that this amine is responsible for their chromaffinity. The concentrations of adrenaline, noradrenaline, 3,4-dihydroxyphenylalanine and 5-hydroxytryptamine were found to be too low to account for the chromaffin reaction. This paper is concerned with the general characteristics and the histochemical behaviour of the cells (for simplicity the cells are called dopamine cells). The dopamine cells contain cytoplasmic granules which may be selectively stained by a nuclear fast red staining method. By use of this method they are clearly distinguishable from other mammalian chromaffin cells. In all essential respects the dopamine cells resemble the catechol amine containing cells in the adrenal medulla. Their cytoplasmic granules show a direct chromaffin reaction with bichromate but no reaction after pretreatment with formalin. The formalin-fixed cells are argentaffin and strongly reduce ferricyanide, and retain their reducing capacity at least partly even after pretreatment with bichromate. The azo-coupling reaction with diazo-safranin is negative. The dopamine cells are clearly distinguished from the enterochromaffin cells by the chromaffin and azo-coupling reactions. The most significant result is that the dopamine and noradrenaline cells, after fixation in formalin or bichromate, have the same histochemical behavior. Since dopamine is chemically closely related to noradrenaline, this is what should be expected if the specific chromaffin cells in ruminant tissues contain dopamine. It is concluded that the results provide further support for the view that the specific chromaffin cells in ruminants store dopamine.