Evidence for the D-cell of the pancreas secreting somatostatin.

By immunofluorescence, somatostatin-, glucagon- and insulin-containing cells are localized in serial sections of the pigeon pancreas. The distribution of the somatostatin immunofluorescent-cells corresponds to that of the D-cells (A1-cells), which are particularly numerous in this animal species. This observation, coupled with the finding of D, A and B-cells at the ultrastructural level, indicates that the D-cell is responsible for the secretion of somatostatin.