Objective To examine the distributions of β-catenin and adenomatous polyposis coli（APC） protein in the tooth germ, and obtain the messages of function of the two factors and the relationship between them. Methods Mice were selected and cohabited with the ratio of female mice to male ones being 2∶1, and Embryo day 0.5 was confirmed based on the finding of vaginal plug. The distributions of β-catenin and APC protein in the Embryos on day 13.5, 14.5, 15.5, 16.5, 17.5 were examined in the paraffin-embedded sections by immunohistochemistry methods. Results During E13.5 d to E17.5 d, positive expression of β-catenin was found in the oral epithelium and the dental lamina, and became more and more strong. The staining were whole cell. During the bud stage, strong positive expression of APC protein was found in the oral epithelium and the dental lamina, but the expression displayed a down -regulation tendency. The staining was the cytomembrane and cytoplasm. There was negative correlation between β-catenin and APC protein（P
