The cytochrome oxidase reaction product differs markedly between liver cells and between individual mitochondria. This patient has a mutation in mt DNA, resulting in a mosaic distribution of cytochrome oxidase activity; the clinical diagnosis is Pearson syndrome. About this case, and more mitochondrial mosaics, see http://www.biomedcentral.com/1472-6890/9/4
Prefixation in glutaraldehyde at 0°C; staining of cryostat sections with DAB at pH 6; postosmication.
