Selective Histochemistry of Glucagon in the a Cells of Pancreatic Islets by Indole Methods

Up to now attempts to provide a selective morphological detection of glucagon in the A cells of pancreatic islets have been carried out by means of im-munohistochernical techniques or indole methods. By immunohistochernistry the presence of glucagon in the cytoplasm of some islet cells has been definitively ascertained, but the exact nature of these cells has not been completely established (Baum et al., 1962; Chiappino et al., 1963). In fact, the most reliable and selective methods for islet cytology are not appliable to fresh cryostatic sections which are required by immunohistochemical techn iques.