In vitro organogenesis of amphibian undifferentiated cells

Abstract

The mechanism of body patterning is complex and includes multiple induction events. Activin, a member of the TGF-β-super family, can induce several kinds of mesodermal and endodermal tissues in the amphibian presumptive ectoderm (animal caps) . The effect of activins on animal caps is distinctly dose dependent, with induction of more dorsal mesodermal tissues and endodermal tissues as the concentration increases. In a recent study of the role of activin in organ formation, we succeeded in raising a beating heart by treating animal caps with a high concentration of activin A. Renal tubules were induced in Xenopus animal caps treated with a combination of activin A and retinoic acid (RA) at a high frequency (100%) accompanying several genes. The renal tubule explants induced by activin and RA in vitro could also function in vivo when the explant was transplanted into the presumptive kidney. Isolated presumptive ectoderm from Xenopus blastula was also treated with activin and retinoic acid to induce differentiation into pancreas. We have already succeeded to make 14 organs and tissues in vitro including sensory organs such as eye and ear vesicle from undifferentiated cells.