Isolation of functional glucagon islets of Langerhans from the chicken pancreas.

Two types of islets of Langerhans are present in the avian endocrine pancreas: glucagon islets (A-islets) and insulin islets (B-islets). Islets from the chicken pancreas were isolated by ductal injection of collagenase, enzymatic digestion, atraumatic dispersion of the digests at an appropriate time, and nylon mesh filtrations. A- and B-islets were identified by immunohistochemistry and radioimmunological quantification of insulin and glucagon. Dithizone-positive islets proved to be mostly of the A-type by immunostaining, and radioimmunological measurements: islets from the cranial half of the body of the pancreas were almost pure (95%) glucagon islets (0.454 +/- 0.027 pmol glucagon and 0.023 +/- 0.005 pmol insulin per islet). Increasing the glucose concentration in the incubation medium from 14 to 42 mM decreased glucagon release, demonstrating that the alpha-cells maintained their glucose sensitivity after isolation.