Neural induction in amphibians : Transmission of a neuralizing factor.

The neural plates of very early neurula stages of Triturus alpestris were removed, the material which is released from the extracellular space between mesoderm and neural plate to the medium in which the embryos were dissected was isolated and extracted with phenol. The protein isolated from the phenol layer showed neural inducting activity. Proteoglycans isolated from the aqueous layer did not show such inducing activity. These results together with previously published experiments (Wilhelm Roux's Arch 184: 285-299) suggest that a neuralizing factor which is released from the mesoderm acts on the inner surface of the overlying dorsal ectoderm.