STIMULATION OF CIRCUS MOVEMENT BY ACTIVIN, BFGF AND TGF-BETA-2 IN ISOLATED ANIMAL CAP CELLS OF XENOPUS-LAEVIS

Lobopodium is a hyaline cytoplasmic protrusion which rotates circumfer encially around a cell. This movement is called circus movement, which is seen in dissociated cells of amphibian embryos. Relative abundance of the lobopodia-forming cells changes temporally and spatially withi n Xenopus embryos, reflecting stage-dependent difference of morphogene tic movements. The lobopodia-forming activity of dissociated animal ca p cells was stimulated strongly by activin and bFGF, and weakly by TGF -beta 2. In addition, activin A was found to stimulate cellular attach ment to the substratum when the cultivation lasted long. Thus, mesoder m-inducing growth factors stimulate lobopodia formation and cellular m ovements which may be necessary for gastrulation and neurulation in Xe nopus early embryos.