The use of the dye neutral red as a specific, non-toxic, intra-vital stain of islets of Langerhans.

The development of improved methods of islet isolation from the pancreas is hampered by difficulty in identification of islets. A method described by Bensley in 1911 uses neutral red to stain the islets selectively. In the present study the method has been simplified and selective staining of islets in the rat, dog and pig demonstrated by use of light and electron microscopy. Staining of islets with neutral red does not appear to affect their viability as judged by insulin secretion and transplantation in rats.