[Autoradiography, in the electron microscope, of endocrine pancreatic cells of a teleost fish, Xiphophorus helleri H].

After using the autoradiographic technique in electron microscopy, we were able to verify that there is no adrenergic innervation in the pancreatic islet of Xiphophorus: nerve fibers and nerve endings do not incorporate tritiated noradrenaline. On the other hand, nerve fibers outside the islet, in the mesenteron or in the exocrine pancreas, are labelled.