Abstract
Spontaneous gastric carcinoids were observed in a 104-week-old male and a 112-week-old female Crl: CD (SD) Br rat. The tumors showed intramucosal proliferation and gave positive results in argyrophilic reaction. Ultrastructurally, variable numbers of electron-dense or electron-opaque secretory granules were observed in the cytoplasm of the tumor cells. These tumors were considered to be of enterochromaffin- like (ECL) cell origin.
