Cloned Mice: DISCUSSION(3)
A confounding variable in our comparison of cytoplast types was the use of ethanol versus SrCl2 for activation. Ethanol was used in our study because of its apparent success in yielding cloned mice from cumulus cells following IE of B6D2F1 oocytes. Activation using ethanol has also used successful in goat cloning by somatic cell nuclear transfer. However, activation using SrCl2 is better established in mouse cloning and may well yield a superior cytoplast because of its capacity to more closely mimic calcium transients elicited by fertilization. By contrast, ethanol activation has been shown to elicit only a single calcium transient, which when it occurs in the absence of an intact microtubule spindle will fail to initiate development. canadian neighbor pharmacy online
Although we did not evaluate microtubule spindle integrity immediately after transiently treating activated oocytes with demecolcine, a transient disruption could have impeded the cytoplasmic response to a previously applied activation stimulus. In this regard, the use of ethanol as an activating stimulus to create cytoplasts for nuclear transfer would be distinct from its capacity to make parthenogenetic embryos, the latter of which we exemplified in our study. Thus, the developmental competence of cytoplasts treated for IE possibly could be improved by activating with agents such as SrCl2.