Fig. 1. The size of neural crest explant cultures increases in response to FGF2 in a dose-dependent manner. In the presence of 0.1 ng/ml (n=10) or 1 ng/ml FGF2 (n=10), neural crest cultures undergo enhanced proliferation compared with cultures grown in the absence of FGF2 (n=12) or in the presence of 10 ng/ml FGF2 (n=10). Explant growth is expressed as the increase in the percentage of the explant diameter with time. Values are mean±s.e.m. (for 5 and 10 days only for clarity of presentation).