Correlation between the cell cycle in the neurectoderm and differentiation during the early development of Xenopus laevis. 2 Inhibition of DNA synthesis and mitosis during gastrulation.

The hypothesis that cell differentiation during primary induction may be coupled with a 'quantal' cell cycle in the presumptive neurectoderm is considered. Embryos of Xenopus laevis were incubated with fluorodeoxyuridine or mitomycin C during gastrulation or neurulation. Embryos treated during the gastrula stage developed abnormalities of the brain but not of other tissues. This is seen as lending support to the idea that the wave of DNA synthesis and mitosis in the presumptive neurectoderm during gastrulation is an important event in the process of primary induction.