THE OCCURRENCE OF ACIDIC FIBROBLAST GROWTH FACTOR-LIKE IMMUNOREACTIVITY IN SUBPOPULATIONS OF ENDOCRINE-CELLS IN THE PANCREAS AND INTESTINE OF THE RAT

A study of the immunocytochemical localization of acidic fibroblast growth factor (aFGF) in the rat digestive system using a polyclonal anti-aFGF antiserum revealed immunoreactive cells in the periphery of the islets of Langerhans and in the mucosal epithelia of the intestine, from the jejunum through the colon. In the pancreatic islet, light microscopic immunostaining of consecutive sections with anti-aFGF and anti-glucagon antisera as well as pre-embedding immune-electron microscopy demonstrated that aFGF-like immunoreactivity belongs to the A cell. In the intestinal epithelium, the aFGF-immunoreactive cell was simultaneously reactive to anti-glucagon antiserum and was ultrastructurally identified as the L-cell, which is known to produce glucagon-like immunoreactants derived from proglucagon. Post-embedding immune-electron microscopy further revealed that the immunoreactivity is localized in the secretory granules of A- and L-cells. These results suggest that an aFGF-like immunoreactant occurs in the populations of gasrto-entero-pancreatic endocrine cells that express proglucagon.