Peroxidase and cytochrome oxidase in the Walker carcinoma 256.

It has been previously reported (7) that the administration of estrogens to the ovariectomized rat causes a pronounced response in the peroxi dase level of the uterus. Since the estrogens stimu late mitotic activity in the uterus, it was thought that the presence of peroxidase might be charac teristic of tissues undergoing proliferation. The studies to be presented in this paper mdi cate that a peroxidase, similar to the one described for rat uterus, is present in the Walker carcinoma 956 of rats. Parallel studies on the cytochemical distribution of peroxidase and cytochrome oxidase are also reported.