Someone else’s cells

You probably have someone else’s cells growing inside you.

In a phenomena known as microchimerism, mothers pass some of their cells onto their children, and vice versa, during pregnancy. That’s not too surprising in itself. What is more surprising is that these cells can reproduce for decades. It’s not uncommon to find female cells in a grown man, or male cells in a woman who gave birth to a son.

See “Your Cells Are My Cells” in Scientific American, February 2008.