Fig. (12) Electron microscopic radioautogram of the adrenal medullary tissues of an aged adult mouse at postnatal month 6, labeled with 3H-thymidine, showing DNA synthesis (several silver grains) in the nuclei as well as in a few mitochondria of 2 adrenalin cells at center and 2 noradenalin cells at lower left and right. x 3,000. (From Nagata [49]. Courtesy of J Cell Tiss Res 9: 1793-1802, 2009).