Fig. (13) Electron microscopic radioautogram of the adrenal
medullary tissues of a senescent adult mouse at postnatal month 12
(year 1), labeled with 3H-thymidine, showing DNA synthesis
(several silver grains) in the nuclei as well as in a few mitochondria
of a noradrenalin cell at center right and several adenalin cells at
left and lower left and right. x 6,000.