[Cytoplasmic control of cell division in amphibians: changes in the timing of egg cleavage after injection of heterospecific cytoplasm].

Cytoplasm of Xenopus laevis virgin eggs is injected into fertilized eggs of Pleurodeles waltlii, species characterized by an initial development slower than that of Xenopus. The cytoplasm introduced into eggs at the 2 or 4 cell stages accelerates the division of cells in the site of injection, Later on synchronism of cleavage for the different blastomers of operated eggs reappears. The effects of an heterologous cytoplasm on mitosis and endogenic rhythm of cleavage are discussed.