Poly (A) . oligo (dT)-stimulated DNA polymerase activity in preimplantation mouse embryos.

DNA polymerase activity with Poly (A) . oligo(dT) as a template-primer has been found in preimplantation mouse embryos. A sharp increase in enzyme activity was observed at the time of formation of inner cell mass (ICM) and trophoblast cells. Differential inhibition of enzyme activity before and after ICM formation raised the possibility that more than one Poly(A) . oligo(dT)-directed DNA polymerase was detected.