Getty Images
Normal development is an inefficient process – only 31 of every 100 human conceptions complete the journey. Development via somatic cell nuclear transfer (SCNT), under the direction of adult DNA from a specialized cell is even less efficient, with success rates of about one in 300 or worse. Although nearly as many questions remain as when SCNT was first attempted half a century ago, researchers are closing in on why it is so difficult to emulate normal development starting with this most unusual genetic headquarters.
The major distinction between development via sperm and egg versus SCNT is a profound perturbation of gene expression. The deviations arise from various sources, including influences of the culture medium and factors in the nucleoplasm and cytoplasm. When all goes well, morphogens interact to effectively reprogram the new nucleus, which is vital to resetting the developmental program. But even the most prominent researchers ...
