Cell differentiation in ascidian studied by nuclear transplantation.

The egg of the ascidian Ciona Intestinalis was divided 20 min after fertilization into two fragments, one nucleated and the other non-nucleated. Nucleus of ectodermal, mesodermal, or endodermal cell, taken from gastrula or tail-bud embryo was transplanted into the non-nucleated fragment. The fragment developed into abnormal or partial embryo, of which the cells or tissues were differentiated mainly according to the regional distribution of presumptive organ-forming substances of the egg cytoplasm that the fragment contained.