Abstract: To probe into the embryotoxicity , the teratogenic effect of sodium selenite as well as it teratogenic dosage and characteristics were studied. Methods : The body weight , body length and tail length of fetuses were measured , the death rate of fetuses and the rate of absorbed embryos were counted , the external appearances and internal organ malformations were observed , ossificated gradation of supraoccipital bone , ossification centers in caudal , forelimb and hindlimb , as well as degree of ossification agenesis in sternebrae were graded and counted. Statistics analysis was made with analysis of variance , chi2square and rank2sum test .Results : The low dosage (0. 6 mg/ kg·bw) was ineffective. In middle (3 mg/ kg·bw) and high (15 mg/ kg·bw) dosage groups , there were agenesia of supraoccipital bone , sternebrae , forelimb and hindlimb in fetuses and the differences were significant ( P < 0. 05～0. 005) comparing the two groups with the cont rol group. Conclusion Sodium selenite possesses embryotoxicity , it s toxicity dosage for mice is 3 mg/ kg·bw and above ; it causes only mouse embryo or fetus ossification agenesis and development retardation.

Key words: sodium selenite, teratogenicity, embryotoxicity