Evidence for the Presence of A-Cells in the Endocrine Fetal Pancreas of the Rat

With the electron microscope, typical endocrine pancreatic A-cells have been identified in fetal rat pancreas from 18 days of gestation to birth. Earlier gestational stages have not been studied. The A-cells were seen both in tissue fixed immediately and in tissue maintained under organ culture conditions for one or more days. A-cells were less numerous than B-cells in all instances. These morphological observations were confirmed by the detection of measurable glucagon-like immunoreactivity in fetal rat pancreas obtained at the same stages of gestation.