Abstract: Quantitative laser microtomography was employed to measure the single cell volume. NMRI mouse zygotes and 2-cell embryos were shown to exhibit the shrinkage at apoptosis induced with ROS (40 min., H2 O2 , 0.2 mM). Unlike early embryos, there was no influence of in vitro apoptotic circumstances on mature oocytes, direct precursor of early embryogenesis. Dulbecco’s solution prepared from electrochemically reduced bi-distilled water allows the low redox potential in both normal and apoptotic conditions. The data obtained permit us to suggest that ROS sub-milimolar concentrations likely act as the signaling impact. Cys-loo receptors containing thiol group may be considered as the target of hydrogen peroxide molecules.