Homoiogenetic Neural Inducing Activity of the Presumptive Neural Plate of Xenopus Laevis

Heteroplastic combinations were made between Xenopus laevis presumptive neural plate and competent ectoderm of Xenopus borealis. Primarily induced presumptive neural plate cells (Xenopus laevis) can easily be distinguished from Xenopus borealis cells by specific quinacrine fluorescence of the nuclei. It was clearly shown that presumptive neural plate, which has primarily been induced by the underlying chordamesoderm exerts homoiogenetic inducing activity on competent ectoderm. The inducing activity is increased in pieces of presumptive neural plates, when the superficial layer has been removed from the adjacent deep layers. The enhancement can be explained by the fact that the removal of the superficial layer acting as barrier allows the inducing stimulus to be easily propagated from the apical (distal) side of the deep layers of the presumptive neural plate.