Differentiation and transdifferentiation of adrenal chromaffin cells of the guinea pig. II. Adrenal medullary explants grown in tissue culture.

Explants of adrenal medullary tissue taken from newborn guinea pigs were grown in culture for up to two weeks. The explants exhibited sparse outgrowth of neurite-like processes, in contrast to adrenal medullae taken from young postnatal rats or adults guinea pigs that were (i) grown under identical conditions (Unsicker and Chamley 1977) or (ii) transplanted to the anterior chamber of the eye (Unsicker et al. 1981), respectively. Nerve growth factor (10-100 ng/ml, 2.5 S NGF) did not enhance formation of processes. However, electron-microscopic investigations revealed the presence of numerous processes within the explants, which extended from chromaffin cells and were characterized by longitudinally oriented cytoskeletal structures, various population of clear and dense-cored vesicles, varicosities and growth cones. Chromaffin cell bodies largely resembled their in situ-counterparts, but had fewer and smaller storage vesicles than controls. The results are discussed in light of recent findings regarding the potency of NGF and NGF-like growth factors to induce neuronal transdifferentiation of adrenal chromaffin cells.