Fig. (1) Electron microscopic radioautogram of the adrenal medullary tissues of a mouse embryo at fetal day 19, labeled with 3H-thymidine, showing DNA synthesis (several silver grains) in the nuclei as well as in a few mitochondria of 4 adenalin cells at right and 1 noradrenalin cell at left. x 3,000. (From Nagata [49]. Courtesy of J Cell Tiss Res 9: 1793-1802, 2009).