Cytoplasmic and cortical factors participating in cleavage furrow formation in eggs of three amphibian genera; Ambystoma, Xenopus and Cynops.

A cytoplasmic factor and a cortical factor participating in cleavage furrow formation had been previously found in Cynops eggs (Sawai, 1972). These were investigated in the present study in Ambystoma and Xenopus eggs, by the method of cytoplasmic or cortical transplantation. Results were practically similar to those previously obtained with Cynops, indicating that in all the species of eggs during cleavage, the cytoplasm localizing along the cleavage furrow possessed furrow-inducing activity, and the cortex was competent to form the furrow in response to the activity of the cytoplasmic factor. In the present work, the species specificity of the two further factors was examined among Cynops, Ambystoma and Xenopus eggs, and the factors were found to act across species.