Ultrastructural evidence for the presence of enterochromaffin type II cells in the pancreatic islets of the rabbit.

Numerous papers on the fine structure of mammalian pancreatic islet cells have been published, and six types of cells have been recognized on the basis of ultrastructural differences. The cellular types normally found in the islets of the rabbit are the A, B, and D cells. We describe here a rare type of cell with ultrastructural features different from these, which we have found in the islets of the rabbit. The morphological characteristics of these cells are the same as those described as type II enterochromaffin cells in the rat intestine.