Effects of treatment with embryonic and uterine tissue homogenates on Lewis lung carcinoma development.

Based on the hypothesis that the development of cancer is actively inhibited during embryonic life, the effects on tumor growth of homogenates of different tissues (embryos, uteri at ninth day of pregnancy, non-pregnant uteri and normal liver) were investigated in syngeneic C57BL/6 female mice. Primary tumor growth and spontaneous pulmonary metastasis formation were completely suppressed in the group of mice treated with pregnant uteri homogenates. Embryos, non-pregnant uteri and normal liver homogenates were ineffective.