Mitochondrial inclusions in human cancer of the gastrointestinal tract

Four cases of adenocarcinoma of the gastrointestinal tract have been examined. Large electron-dense mitochondrial inclusions were found in the mitochondria of many cells; after detailed histochemical tests they could be classified into two types. The first type of inclusion consisted of clusters of electron-dense, calcium-containing granules linked to a glycoproteic substrate. These inclusions were linked to a glycoproteic substrate. These inclusions were always associated with cristae and were found in the mitochondria of cells that showed clear signs of degeneration. The second type of inclusion was found much more frequently and consisted essentially of phospholipids of which electron density was strictly osmium dependent. Their structure was usually at least partly lamellar, but in some cases it was homogeneous throughout. It is hypothesized that inclusions of the second type may have the same biological role as the morphologically identical inclusions found in the mitochondria of brown fatty tissue in the perinatal rat and in yeasts during glucose repression or anaerobiosis. The resemblance between the homogeneous variety of inclusions within the second type and the mitochondrial inclusions recently described in human leukemic lymphoblasts and monoblasts has been stressed to bring out the need for a histochemical check on the supposedly viral nature of the latter inclusions.