['Rats with nitrofen-induced congenital diaphragmatic hernia (CDH) have hypoplasia and malformations of the heart. The mechanism of action of nitrofen involves changes in neural crest signaling. Pax3 function is required for cardiac neural crest cells to complete their migration to the developing heart. Vitamin A improves heart hypoplasia. The aims of this study were to examine whether Pax3 expression is decreased in the heart of E13 E15 and E21 rats exposed to nitrofen and if vitamin A reverts this effect.', 'Pregnant rats received either 100 mg nitrofen or olive oil on E9.5. Each group was divided into 2 subgroups according to the subsequent treatment with intragastric vitamin A (15000 IU) or vehicle on E10.5 to E11.5. The pups were recovered on E13, E15 and E21 and the hearts were dissected out. Pax3 mRNA expression was determined by quantitative real time PCR. Comparisons among groups were made with ANOVA and Bonferroni post hoc tests with a threshold of significance of P < .05.', 'Pax3 mRNA expression was significantly decreased on E13 and E15 in the hearts of nitrofen-treated embryos and it remained decreased although not significantly on E21. Vitamin A recovered this expression on E13, partially on E15 and above normal levels on E21.'] Does vitamin A improve Pax3 expression that is decreased in the heart of rats with experimental diaphragmatic hernia?