Your Cell Are My Cells

摘要

"Icontain multitudes," says a line in Walt Whitman's poem "Song of Myself." Whit- man was not thinking in biological terms, but the line has biological resonance. Recent studies suggest that each of us possesses-in addition to the trillions of cells descended from the fertilized eggs we once were-a cadre of cells we have acquired from other, genetically distinct individuals. In utero we receive an infusion of them from mom. And women who become pregnant also collect a sampling shed by the developing embryo.