Table 1.

Characterization of cellular subtypes in compact pancreatic Langerhans islets [31,32].

Type	% 1	Location in Compact Islets	Ultrastructure	Secretion
B (beta)	60–70%	Center	Granules with crystalloid	Insulin
A (alpha)	15–20%	Periphery	Eccentric electron-dense material	Glucagon
D (delta)	10–15%	Periphery	Small, uniformly electron-dense granules	Somatostatin
PP	5%	Nonspecific	Granules with variable electron density or homogeneously electron-dense (depending on area)	Pancreatic polypeptide

¹ Represents the percentage of cells belonging to a specific subtype out of the total cellular population of compact pancreatic Langerhans islets.