Effect of maternal urethane administration on the manifestation of cleft lip and palate in CL/Fr mice.

Abstract

To determine whether the administration of urethane also decreases the associated cleft palate in CL/Fr mice, pregnant CL/Fr mice (30% of their offspring have spontaneous cleft lip with associated cleft palate [CL/P]) were treated with various doses of urethane on different days of pregnancy. In the groups treated with 250, 500, and 750 mg/kg urethane on day 9 of pregnancy, the frequency of CL/P decreased with the dose to 18%, 14%, and 11% of term fetuses, respectively. In the group treated with 1,000 mg/kg urethane on day 9, the frequency of CL/P decreased to 6%, but isolated cleft palate (CP) was observed in 23% of term fetuses. Most fetuses in the same group had severe tail anomaly (absence of tail or stub tail), and showed marked loss in body weight. The CP observed in the group treated with 1,000 mg/kg urethane on day 9 might possibly be due to the teratogenicity of the drug.