(A) Neuronal and chromaffin differentiation of spheres. 7 d old spheres adhering to poly-D-lysine/fibronectin-coated coverslips were differentiated for 6 d in differentiation medium containing ATRA and ascorbic acid (for neuronal differentiation) or dexamethasone and PMA (for chromaffin cell induction). Immunocytochemistry images show spheres cultured with or without specific factors as indicated and stained for β3-Tubulin, peripherin, TH, DBH and CHGA. Nuclei were counterstained with DAPI. Scale bars equal 100 µm. Quantification of positive cells is shown in histograms (1994 cells of two independent experiments were analyzed). Statistical analysis was performed using the t-test. *, p<0.05; **, p<0.01; ***, p<0.001. (B) Chromaffin cell inducing conditions upregulate catecholamines in spheres. HPLC analysis of catecholamine content in lysates of spheres differentiated in adherence for 6 d in differentiation medium supplemented with or without dexamethasone and PMA. The means of three independent experiments are shown. Statistical analysis was performed using the t-test; n.s., not significant; *, p<0.05.