This model of a molar shows color-coded barium banding patterns that reveal weaning age. Ian Harrowell, Christine Austin, Manish Arora/Harvard School of Public Health hide caption

itoggle caption Ian Harrowell, Christine Austin, Manish Arora/Harvard School of Public Health

Fungi (cyan) surround a human hair within the skin. A study in the journal Nature shows the population of fungi on human skin is more diverse that previously thought. Alex Valm, Ph.D. hide caption

itoggle caption Alex Valm, Ph.D.

Nanoflowers, each smaller than the thickness of a dollar bill, sprout up spontaneously on a surface dipped in salts and silicon. Courtesy of Wim Noorduin/Harvard University hide caption

itoggle caption Courtesy of Wim Noorduin/Harvard University

After President Obama overturned Bush-era policy restricting federal funding of embryonic stem cell research in 2009, Nebraska Right to Life led a protest of the research outside the University of Nebraska regents' meeting. Nati Harnik/AP hide caption

itoggle caption Nati Harnik/AP

Human embryos grow in a petri dish two days after scientists in Oregon cloned them from a donor's skin cell. http://www.flickr.com/photos/ohsunews/8726915230/in/photostream//Courtesy of OHSU Photos hide caption

itoggle caption http://www.flickr.com/photos/ohsunews/8726915230/in/photostream//Courtesy of OHSU Photos

A scientist removes the nucleus from a human egg using a pipette. This is the first step to making personalized embryonic stem cells. Courtesy of OHSU Photos hide caption

itoggle caption Courtesy of OHSU Photos

A miniature ninja throwing star or a surgical device? The microgripper, shown here coming out of a catheter tube, is activated by body heat. The sharp appendages fold up when the device warms up. Evin Gultepe, Gracias Lab, Johns Hopkins University. hide caption

itoggle caption Evin Gultepe, Gracias Lab, Johns Hopkins University.

A microscopy image of a rat pancreas shows the insulin-making cells in green. Masur/Wikimedia.org hide caption

itoggle caption Masur/Wikimedia.org

In this Jan. 18 photo provided by the NYU Langone Medical Center, a technician examines mice to determine their health at the hospital's complex in New York. New York University/AP hide caption

itoggle caption New York University/AP

Musician Jake Orrall performs onstage at the Coachella Valley Music & Arts Festival on April 14. Temporary hearing loss following concerts and other loud events may protect our ears from more permanent damage. Frazer Harrison/Getty Images for Coachella hide caption

itoggle caption Frazer Harrison/Getty Images for Coachella