MG⁺⁺-DEPENDENT ADENOSINE TRIPHOSPHATASE ACTIVITY IN PREIMPLANTATION MOUSE EMBRYOS

Abstract

Mg⁺⁺-dependent adenosine triphosphatase (Mg-ATPase) activity was cytochemically investigated in preimplantation mouse embryos. This enzyme activity was demonstrated on the cell surface of unfertilized and fertilized eggs, blastomeres in cleavage-stage embryos and blastocysts. In blastocysts, however, only trophectodermal cells were positive for this enzyme reaction. Among these cells, mural trophectodermal cells had more intense activity of Mg-ATPase than polar trophectodermal cells. Inner cell masses of blastocysts showed absolutely no Mg-ATPase activity.