Printed in Great Britain 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 induc-ing decidual formation. One implant produced by an isolated blastomere from a 4-cell egg contained a small, retarded embryo at 5 £ 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