Radioautographic Study of Interkinetic Nuclear Migration in the Neural Tube.∗

Conclusion Radioautographs of early neural tube of chick embryos treated with thymidine-H3 for varying intervals of time give evidence substantiating the concept of inter-kinetic migration of nuclei. Synthesis of DNA occurs only in nuclei of peripheral part of wall, and does not take place in those of juxta-luminal zone. The period of DNA synthesis continues for at least 4 hours, but does not extend much beyond this time.