Cell cycle of neural crest cells in the early migratory stage in vivo

Abstract

Abstract. The fact that directional migration of neural crest cells (NCC) in vivo occurs in narrow pathways at high cell density, together with our preliminary results showing their high proliferative behaviour, supports the view that a ‘population pressure’ could be an important factor in the mechanism of early dispersion of NCC.The purpose of this work was to establish the cranial proliferative pattern of chick embryo NCC during their early migratory stage in vivo. Growth rates and parameters of cell cycle were obtained from cell populations at several cephalic levels by means of autoradiography after labelling with [3H]dT. The labelled cell index of NCC (Forebrain, 0.288; Midbrain, 0.206; and Hindbrain, 0.134) was significantly greater than in other cells populations (e.g. for the neural tube cells: 0.085, 0.030, and 0.031, respectively). The cell generation time was the shortest in NCC (16 h), compared to ectoderm (33 h), mesoderm (58 h) and endoderm (72 h). The duration of the cell cycle phases for NCC were: M, 0.29 h; G1, 11.23 h; S, 3.40 h; and G2, 1.02 h.These quantitative results show that NCC have the greatest proliferative rate in young chick embryos. In relation to cranial regions, the data are consistent with the idea that, in the early migratory phase of this cell population in vivo, migration is in part driven by population pressure.