Fig. 6. Influence of different factors on the level of chondrogenic differentiation achieved by neural crest cells when cultured for 10 days in the presence of 10 ng/ml FGF2. (A) Explants of varying sizes display no significant differences in the number of cultures undergoing chondrogenesis (t-test: P<0.4). (B) Neural crest obtained from embryos which were of approximately 6 hours difference developmentally, exhibit no significant difference in incidence of chondrogenesis (t-test: P<0.4). (C) The cranial axial region from which the neural crest originates determines skeletogenic response to FGF2 signalling: explants from the fore- and hindbrain region show a markedly reduced capability of differentiation when compared with those from the midbrain (t-test: P<0.001 for both comparisons).