[Spatial-temporal patterns of the cell cycles in embryos of the clawed toad during gastrulation and neurulation].
The dynamics of DNA synthesis and duration of G2-phases in different dorso-ventral zones and cell layers were studied using 3H-thymidine in the X. laevis embryos during gastrulation and neurulation. Gradients of the index of labelled nuclei and of the rate of 3H-thymidine incorporation decreasing in the ventro-dorsal direction were observed during the whole period of gastrulation. In the end of gastrulation a wave of increase of the index of labelled nuclei and of the rate of 3H-thymidine incorporation proceeds in the same direction and, as a result, both the gradients are inverted. A high positive correlation was found between the simultaneously registered indices of labelled nuclei in different cell layers of the same dorso-ventral zones. The data were obtained suggesting the ventro-dorsal migration of cells in G2-phase. A conclusion is drawn that the regulation of cell cycles during gastrulation--neurulation obeys integral laws among which the waves of cell entrance in S-phase play an important role.
D000818:Animals; D002453:Cell Cycle; D002467:Cell Nucleus / Q000648:ultrastructure; D004247:DNA / Q000096:biosynthesis; D005775:Gastrula / Q000166:cytology*; D007399:Interphase; D008940:Mitotic Index; D009420:Nervous System / Q000196:embryology*; D013997:Time Factors; D014982:Xenopus laevis / Q000196:embryology*
D004247:DNA
Prostranstvenno-vremennýe zakonomernosti kletochnykh tsiklov u zarodysheĭ shportsevoĭ liagushki v period gastruliatsii i neĭruliatsii.