Postimplantation development of blastomeres isolated from 4- and 8-cell mouse eggs.

Blastomeres isolated from 4- and 8-cell mouse eggs were inserted into empty zonae and transferred to the oviduct. The products of both types of blastomere were capable of inducing decidual formation. One implant produced by an isolated blastomere from a 4-cell egg contained a small, retarded embryo at 5 1/2 days but most decidua from blastomeres of either 4- or 8-cell eggs contained only a few trophoblast giant cells. It is suggested that this lack of totipotency is due to insufficient cells being present at cavitation rather than restriction in developmental potential.