ABSTRACT
The Pancreatic islets of rats were demonstrated after perfusion with Kanovski- Dithizon by Scanning electronmicroscopy. The results are summed up as follows: Pancreatic islets are closely surrounded by a proper membrane formed by two layers of reticular and collagenous fiber nets. B-cells are polygonal and average 10 ?m in diameter. The surfaces of B-cell are characterized by cytoplasmic projections and blebs, while those of A-cell have few characteristics, A-cells show a momopolar and B-cells a polypolar type of secretions, The inner surfaces of B-cells are characterized by "secretion canaliculus" (insulin canaliculus) and "secretion pore". The secretions canaliculus and secretions pores are the passage through which the secretion Passes into the calpillary net or sinus of the islets.