Each of us probably harbors some maternally derived cells. When my co-workers and I took a single blood draw from healthy adults and tested the equivalent of about 100,000 cells, we found maternal microchimerism in about 20 percent of subjects. But that is a minuscule portion of blood and does not take into account cells that could be in tissues-something that is possible, but challenging, to examine in humans.
展开▼
