Acute leukemic cells. Qualitative and quantitative electron microscopy.

Quantitative and qualitative electron microscopic studies were performed on the leukemic cells of 3 patients with stem cell leukemia, 6 patients with acute lymphoblastic leukemia, 7 patients with acute monoblastic leukemia, 3 patients with acute myeloblastic leukemia and 7 patients with acute monomyeloblastic leukemia. Significant quantitative differences were noted between some of the leukemic cells in heterochromatin:euchromatin ratios, cell size, granules per cell, amount of endoplasmic reticulum and the number of polyribosomes. Qualitative abnormalities which were found in some cells of all the leukemic groups were observed. These abnormalities included nuclear pockets, deep nuclear indentations (usually not the stem cell), nucleosomes, dilated perinuclear spaces, centrioles located in nuclear pockets (not in the stem cell or lymphoblast), accumulation of microfibrils (greatest in the monoblast and myeloblast), disrupted mitochondria with virus-like particles (none in stem cells), smaller granules and mitochondrial DNA, glycogen, and myelin whorls. The presence of the smaller granules in disrupted mitochondria and the resulting clear areas is probably related to the deranged carbohydrate metabolism of these cells. The presence of virus-like particles within mitochondria may be extremely important, but requires much more investigation. Some of the above findings may offer clues to further investigation of the acute leukemic cell.