[Embryonic induction and role of activins during early amphibian development]

Growth factors are known to act for the formation of the animal tissues and organs. We showed that activins, members of the TGF-beta family growth factors, exist in early amphibian embryos and induce mesoderm tissues and organs in undifferentiated blastomeres (animal cap). Activins are characteristic in that they can establish embryonic body axis, by inducing different mesoderm and endoderm organs depending on their dose. The action of activin seems to be a primary important phenomenon which commonly create the body pattern of vertebrate embryos.