A juxtaposition between A-cells and D-cells in the chicken pancreatic islets following vagotomy

Conventional electron microscopy and enzyme-cytochemistry were applied to elucidate the juxtaposition between the pancreatic D-cell and A-cell, 1-2 weeks after abdominal vagotomy in chickens. A pancreatic D-cell frequently encircled an A-cell. Around this juxtaposition, several D-cells, characterized by the occurrence of peculiar dense bodies, formed a cluster. Both the D-cell and the A-cell juxtaposed with each other and had an irregularly shaped nucleus with several indentations. Exocytosis of secretory granules from D-cells encircling an A-cell was often observed in the capillary side, but no release of secretory granules from A-cells was detected, except on the capillary side. A few large dense bodies, resembling a multivesicular body, were observed in the A-cell cytoplasm, showed positive acid-phosphatase activity, and contained remnants of several types of cell organelles. They thus seemed to be secondary lysosomes. It is possible that the juxtaposition between the A-cell and the D-cell may be morphological evidence of the inhibitory action on the A-cell by the D-cell.