Narrowing the embryologic window of the adriamycin-induced fetal rat model of esophageal atresia and tracheoesophageal fistula.

We recently reported on a new fetal rat model of esophageal atresia (EA) with tracheoesophageal fistula (TEF) induced by prenatal exposure to adriamycin (1.75 mg/kg i. p. injected daily to the pregnant dam from the 6th to 9th gestational days). With this treatment regime, many fetuses were resorbed and the number of associated malformations was very high. The present study demonstrates that similar doses of the drug administered only on the 8th and 9th gestational days allow higher fetal survival (9.7 ∓ 3.9 vs. 6.8 ∓ 4.7 fetuses per litter, P < 0.01) with a similar incidence of EA-TEF (41.2% vs. 56.4%, n. s.) and decreased occurence of associated anorectal and genitourinary malformations. Since this model is an instrument for further investigation of the disturbed cellular and morphogenetic events leading to EA and TEF, the narrowing of the embryologic window obtained by the present study will allow better focusing of the research on the critical period of time involved.