Neural-inducing activity of newly mesodermalized ectoderm.

The neural-inducing activity of artificially mesodermalized ectoderm was examined. The competent ectoderm of earlyCynops gastrula was mesodermalized by being placed in contact withCarassius swimbladder. The mesodermalized ectoderm was combined with ectoderm isolated from various developmental stages of a gastrula. Neural differentiation were observed in half the combinants, even in 18 h ectoderm, which is considered to have lost its neural competence within 6 h. This indicates that mesodermalized ectoderm is capable of inducing neural tissues at the very time it comes into contact with 18 h ectoderm. From the present study, the neural-inducing activity of mesodermalized cells may possibly be closely connected to the early process of their mesodermalization.