Enzyme content of hepatocellular lysosomes in the tumour-bearing rat.

An increase in the number of hepatocellular lysosomes is detectable with the electron microscope in rats bearing a carcinogen-induced sarcoma but not in rats bearing a transplanted Walker tumour. Biochemical studies show an increase in lysosomal enzymes in the liver of both groups of rats, but the increase in the rats bearing a carcinogen-induced sarcoma was greater than that in rats bearing a Walker tumour. This difference is explained by the fact that only gross increases in lysosomal population are likely to be detected in the small samples examined with the electron microscope, but by biochemical methods whereby many grams of tissue are analysed, finer changes may be detected. The collective data to date indicate that an increase in hepatocellular lysosomes and/or lysosomal enzymes occurs in rats and man bearing a variety of tumours and to this there is, as yet, no known exception.