Microbodies of Morris hepatomas.

Summary The structure of microbodies, when present, and the activities of three microbody enzymes (catalase, urate oxidase, and d-amino acid oxidase) were studied in 35 transplantable hepatomas. Microbodies are absent in hepatomas 3683, 7794A, and BRL-4-C-3. The number, size, and often the internal structures of microbodies in the other hepatomas generally reflect the growth rates and, to a certain extent, the amount of enzyme activity in homogenates. Thus fast-growing hepatomas contain only a few small microbodies, usually without crystalloids, most likely reflecting the general absence or low level of both urate oxidase and d-amino acid oxidase activity. On the other hand, microbodies of hepatomas with intermediate growth rates are more abundant, larger than those of fast-growing tumors, and generally have crystalloids. Slowly growing hepatomas have abundant and large microbodies. These fine structural features of microbodies often correlate with enzyme activity. Therefore, hepatomas with high catalase and d-amino acid oxidase activities have numerous large microbodies. Hepatomas with high urate oxidase activity have large crystalloids in the microbodies. While catalase activity of hepatomas roughly correlates with hepatoma growth rates, urate oxidase and d-amino acid oxidase activities do not. It is not uncommon to find very high urate oxidase activity in hepatomas with intermediate growth rates.