Mesoderm and Neural Inductions on Newt Ectoderm by Activin A: (mesoderm induction/newt embryo/activin/EDF)

Mesoderm-inducing activity of human recombinant activin A was examined on presumptive ectoderm of the Japanese newt, Cynops pyrrhogaster, by using the animal cap assay, Activin A induced neural tissues and mesodermal tissues such as brain, neural tube, notochord, muscle, mesenchyme, coelomic epithelium and blood-like cells after 14 days cultivation. These tissues were induced by activin A at concentrations ranging from 0.5- 100 ng/ml. Dose-dependent inducing activity of activity A on newt ectoderm was slightly different from that on other animals, including Xenopus. Wide range of concentration of activin A (0.5- 100 ng/ml) could induce the neural tube, notochord, mesenchyme and coelomic epithelium on the newt ectoderm. Though the percentage of induced explants (two out of 23 explants, 8.7%) was low, the pulsating heart was induced. This paper showed first that activin could induce the mesodermal and neural tissues in newt presumptive ectoderm. Since activin homologues were present In Xenopus and chick embryos, it is likely that activin may be one of the natural inducers in a wide range of species.