Abstract
Summary
Injection of neutralized acid extracts of histolyzing tail skin from R. catesbeiana larvae undergoing normal metamorphosis into spontaneous mammary tumors of mice caused regression of tumors, as reported earlier. This oncolytic substance retains some activity after 15 months at 5 ±: 2°C. Extracts made of histolyzing R. clamitans tail muscle from larvae undergoing artificial metamorphosis are not oncolytic. In this respect they correspond to R. catesbeiana tail muscle extracts made from normally metamorphosing larvae. Extracts made from histolyzing gills of artificially metamorphosed R. clamitans larvae produce pronounced regression of mammary tumors. The effect of injecting sterile distilled water is practically nil, although the rate of tumor growth may be slightly retarded in some instances. It is concluded that extracts made from histolyzing larval anuran gills, similar to those made from degenerating larval anuran tail skin, contain some substance or substances which exert an inhibitory and regressive influence on spontaneous mammary tumors of mice. The results are statistically significant as compared with the mild regressive influence of control solutions similarly injected.
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