A high resolution digital scan shows the cell-level detail of a rat's kidney during a tour of the U.S. Food and Drug Administration (FDA) headquarters in Silver Spring, Maryland, November 5, 2009. Reuters Pictures 3 weeks ago

A high resolution digital scan shows the cell-level detail of a rat's kidney during a tour of the U.S. Food and Drug Administration (FDA) headquarters in Silver Spring, Maryland, November 5, 2009.