Transplantation of Nuclei in Newt's Eggs

Abstract

ONE of the most fundamental problems, both for genetics and embryology, is that of whether the genes in the nuclei of differentiated tissues retain their full range of capacities, or whether some irreversible alteration affects them. The most direct method of investigating this is to develop techniques which permit the transplantation of nuclei from differentiated cells of one kind into enucleated cells of different developmental potentialities. Briggs and King¹ have reported some attempts in this direction, in which nuclei from blastulæ or early gastrulæ of frogs were injected into uncleaved but fertilized frogs' eggs from which the zygote nucleus had been removed. Nuclei from blastulæ permitted the full differentiation of a normal embryo in a fairly high proportion of cases, those from early gastrulæ in a smaller proportion, whereas those from determined (but not yet differentiated) tissues gave little success, though it remained uncertain whether this was due to technical difficulties or to an incapacity of the genes.