In a cluster of glowing human stem cells, one cell divides. The cell membrane is shown in purple, while DNA in the dividing nucleus is blue. The white fibers linking the nucleus are spindles, which aid in cell division.
Allen Institute for Cell Science
Diane, a 4-year-old chimpanzee, relaxes in the trees at the Chimp Haven sanctuary in Keithville, La., on Aug. 25, 2014. She is one of many chimps who have been moved here from the New Iberia Research Center in Lafayette, La.
Ronald Davis cares for his 31-year-old son, Whitney Dafoe. Dafoe is seriously ill with ME/CFS. His father, a Stanford University professor, is organizing a study of the disorder.
Courtesy of Ashley Davis
Feces contain digested food residue and a wide variety of microorganisms, mostly bacteria, that are adapted to life in the intestines. The gases the microbes produce could help doctors and scientists track and understand changes related to health.
Scimat Scimat/Photo Researchers/Getty Images