Quantitative aspects of the cell cycle in the cranial neural tube of the rhesus monkey (Macaca mulatta) during early stages of gestation.

The generation time of ventricular cells in the cranial neural tube of the rhesus monkey embryo was estimated by means of tritiated thymidine autoradiography at stages 12, 13, and 14 (25-31 d of gestation) relative to that which occurs in the mouse at corresponding stages of development. In the rhesus monkey embryo, the generation time lengthens between stages 12 and 13 of gestation, as is the case in the mouse at comparable stages. However, the generation time in rhesus monkey embryos at stage 13 appears to be longer than that in comparable mouse embryos at 10 days of gestation. Thus, it is possible that temporal differences may occur between the rhesus monkey embryo and mouse embryo in terms of the response of the cranial neuroepithelium to teratogenic insults involving the cell cycle.