Ontogeny of four cell types in fetal rat islets using histochemical techniques.

The pancreas of the fetal rat was collected from the first appearance of the pancreatic bud at 11 days of gestation, and every day thereafter until birth. After birth the neonatal pancreas was collected every day for one week, and at intervals thereafter. Fetal B-cells were stained with Gomori's aldehyde fuchsin at 16 1/2 days, and with the immunofluorescent technique for insulin at 14 days. The A-cells were stained as early as 13 days using the fluorescent antibody technique for glucagon. The D-cells first stained at 17 days with pseudoisocyanin. A 4th cell type was found which stained black with silver nitrate, using a method derived from the Grimelius technique for A-cells. This 4th cell type appeared at 15 days in the fetus, reaching its greatest abundance around 19 days, and then declined in numbers after birth until adulthood, when occasionally one or two cells were found.