BASOPHILIC CHROMIDIA AND MITOCHONDRIA IN NORMAL AND IN TUMOR TISSUE

1. Homogenized tissue mixed with Pyronin Y can be separated by differential centrifugation into red-stained nucleic acid-rich elements—nuclei and chromidia —and unstained nucleic acid-poor mitochondria. Pyronin can thus be useful in preparations of pure mitochondrial suspensions. 2. Chromidia thus obtained correspond to basophilic elements of cytoplasm observed in histological preparations. By electron microscopy, RNA content and sedimentation in gravitational field, they appear as a heterogenous population of granules of various sizes. Their RNA content (basophilic) appears to increase in proportion to decrease in their size and sedimentability. 3. Mitochondria of mouse liver and of certain mouse tumors appear to have a constant proportion of RNA to nitrogen (basophilic quotient). In rat pancreas a higher value was found. 4. Liver, pancreas and tumor tissue show completely different patterns in distribution of basophilia. Tumor tissue is characterized by scarcity of large granules (mitochondria and heavy chromidia), reduction in the amount of small chromidia (microsomes) and predominance of basophilia in non-sedimented smallest nucleoprotein granules. Tumors are thus distinguished from such tissues as pancreas in which mitochondria are also scarce but heavy and light chromidia abundant. 5. A considerable succinoxidase activity was invariably found in large chromidia. This activity was inhibited by incubation with crystalline ribonuclease.