The Ultrastructure of Secretory Cells of the Islets of Langerhans in South American Catfish Rhamdia quelen

Abstract

The present work shows that a detailed description of the ultrastructure of the secretory cells of the South American catfish Rhamdia quelen pancreatic islets is presented. Evidence is offered to support the contention that the α -granules consist of a central and an outer portion of different electron densities and solubilities, that the δ -cells are most probably morphologically altered but viable α -cells, and that the β -granules possibly possess a repeating substructure and may therefore represent an intracellular crystalline storage form of insulin.