Morphogenetic interaction of presumptive neural and mesodermal cells mixed in different ratios.

Cells of the presumptive forebrain region and axial mesoderm of Triturus neurulae were disaggregated and combined in different ratios. The differentiation of the central nervous systen in these explants was dependent on the relative amount of mesodermal cells present: an increase of mesodermal cells resulted in a corresponding increase in the frequency with which caudal structures of the central nervous system developed and a gradual loss of the forebrain formations.