The cell cycle during closure of the neural folds in the C57BL mouse.

An analysis of cellular kinetics during closure of the cranial neural folds in the C57BL mouse at 8 and 9 days gestations was obtained by means of tritiated thymidine autoradiography. At 8 days the short generation time (7.5 h) and high labeling index (61.4%) are evidence of intensive proliferative activity occurring concurrently with significant changes in cell shape and movement during neural fold elevation and approximation.