Simple method for the collection of large numbers of viable pancreatic islets from normal rats is described. This method involves collagenase digestion of the pancreas, followed by the use of Ficoll-Conray discontinuous gradient for the separation of isolated islets from unwanted acinal debris. Ficoll-Conray A solution was prepared by mixing undialyzed12. 5% Ficoll and 33.4% Conray in the ratio2: 1, to make a specific gravity of1. 095and osmolarity of396mOsm/l. The solution B, C, and D, with specific gravities1. 084, 1.072, and 1.048, respectively were obtained by diluting A solution with distilled water. Using Ficoll-Conray gradient, about200viable islets which maintained excellently their morphology and function, were collected consistently from a young adult rat pancreas.

Recently, collagenase digestion has become widely employed for the isolation of islets (Lacy and Kostianovsky, 1967; Moskalewski, 1965; Shibata et al., 1976), since this procedure is not so laborious as microdissection (HellerstrOm, 1964) and permits the collection of a large number of islets. In collagenase digestion, however, the liberated islets must be separated from exocrine pancreas, either manually or by gradient centrifugation. Lacy and Kostianovsky (1976) first suggested the use of sucrose gradients for the separation of islets from acinar debris. This method was not feasible, possibly due to its hyperosmolarity, and was modified by Lindall et al.(1967) who used layered Ficoll as the separating