On the nature of the metachromatic cells of pancreatic islets

Islet cells with cytoplasmic granules metachromatically stained by toluidine blue are found in the pancreas of dog, cat, pig, rabbit, teleostian fish, monkey and man, but not in the rat, mouse and guinea pig; dubious results are obtained on duck and ox islets. These cells do not react with the staining methods for the demonstration of A- and B-cells; conversely, they are silver-impregnated by a modification of Davenport's method, and, at least in dog islets, can be readily identified with dark-field microscopy and stained blue with the Mallory-Heidenhain trichrome stain. No obvious changes of this cell type are found either in synthalintreated dogs or in diabetic men. The Authors suggest that the islet argyrophil-metachromatic cells (A₁-cells of Swedish Authors) are identical with D-cells and very likely represent a morphologically and functionally indipendent cell type.