[Comparative morphology of the endocrine portion of the mammalian pancreas]

The endocrinous part of the pancreas in the mammals under investigation (rats, guinea pigs, cattle, cats and man) comprises A-, B- and D-cells always disposed around capillaries were prevailing in all the animals. They excrete the secretory product immediately into the pericapillary gap. A-cells in rodents and man are located in the periphery of the island and often have no contacts with capillaries. The secretion from A- cells having no contacts with capillaries is released into intercapillary clefts into which the cytoplasmic spiculae of the adjacent exocrinous pancreacytes are turned, capable to overlap them and prevent from the entering of the hormone from the intercellular clefts into the pericapillary gap.