title: Changes in cell proliferation kinetics during organogenesis and differentiation of the brain and optic cup in the chick embryo.
abstract: The kinetics of cell proliferation on during early ontogenesis of the brain and formation of the eye was studied in the chick embryo. Kinetic parameters--the mitotic index (MI), proliferative activity (P), the duration of mitosis (tm) and the generation time (T)--were measured in various regions of the brain and eye cup, using colchicine as a stathmokinetic agent. It was found that MI could be taken as an indicator of P during early development. In stage 11 it is also clear that the shortest T occurs in areas of rapid proliferation. By stage 12, although the generation time in the various regions studied differs, P and MI are approximately the same. A short tm is not always restricted to areas with a high P. P is affected by variation of T rather than by tm or time of any other parameter of the cycle. With increasing age, tm values decrease and T increase, probably owing to the progress of differentiation during embryonic development.
authors.affiliation: Department of Zoology, Faculty of Sciences, Alexandria University, Egypt.
authors.forename: M I
authors.initials: MI
authors.lastname: Michael
authors.forename: M A
authors.initials: MA
authors.lastname: Elzayat
authors.forename: L I
authors.initials: LI
authors.lastname: Ibrahim
mesh_terms: D000818:Animals; D001921:Brain / Q000166:cytology / Q000196:embryology*; D002454:Cell Differentiation / Q000502:physiology; D002455:Cell Division / Q000502:physiology; D002642:Chick Embryo; D005123:Eye / Q000166:cytology / Q000196:embryology*; D007700:Kinetics