Viability of adrenal chromaffin cells in the superior cervical ganglion of young adult and aged rats.

Adrenal medullary tissue was autotransplanted to the superior cervical ganglion (SCG) of aged (26 months old) and young adult (3 months old) rats. Four and 20 weeks after operation, the viability of the transplants was evaluated using the formaldehyde-induced fluorescence (FIF) technique and tyrosine hydroxylase (TH) immunocytochemistry. Four weeks postgrafting, the transplant consisted of a densely-packed group of intensively fluorescent chromaffin cells in both age groups. The cells showed strong TH immunoreactivity and some of them were elongated, but only a few displayed short processes. At 20 weeks, most of the cells were spindle shaped and sent out fluorescent processes and a few of them were transformed toward ganglion-like cells. The results suggest that both young and old adrenal chromaffin cells are able to survive, produce neuronal processes and transform toward a neuronal phenotype in the rat superior cervical ganglion.