Muscle cells are stained green in this micrograph of cells grown from embryonic stem cells in the lab of Masatoshi Suzuki at the University of Wisconsin -- Madison. Cell nuclei are stained blue; the muscle fibers contain multiple nuclei. Nuclei outside the green fibers are from non-muscle cells. Suzuki has developed a new method of growing stem cells into muscle cells that could be more suitable for treating disease. Suzuki hopes to experiment next with animals that model muscular dystrophy and amyotrophic lateral sclerosis.