Some Histological and Histochemical Studies of the Pancreas of the Brasilian Sloth,iBradypus tridactylus/i

摘要

The histological and histochemical study of the pancreas of the three-toed sloth, Bradypus tridactylus, demonstrated that with the methods employed the pancreatic islets are apparently formed by A cells exclusively. Two different types of argyrophilic cells were noticed in the exocrine secretory units when Grimelius’ method was used. The methods for the demonstration of D cells showed negative results. Aldehyde fuchsin-positive granules were only noticed at the apex of the exocrine pancreatic cells. These results are discussed in relation to current hypotheses concerning the evolution of insulin secretion mechanism