Abnormal separation of the respiratory primordium in the adriamycin mouse model of tracheoesophageal malformations.

BACKGROUND/PURPOSE: Organogenesis relies on temperospatially coordinated signaling systems. The adriamycin rat model provided insights into the dysmorphogenesis of tracheoesophageal malformations. An adriamycin mouse model (AMM) would facilitate the investigation of their molecular pathogenesis. To transfer the knowledge gained from the rat, we describe a histological account of the critical period of organogenesis of these malformations in the AMM. METHOD: CBA/Ca mice were accurately time-mated (n = 18). Dams received intraperitoneal injections of adriamycin (6 mg/kg) (n = 12) or saline control (n = 6) on days 7 and 8. Fetuses were harvested on days 9, 9.5, 10, 11, 12, and 13, resin embedded, and 1-mum sections of the developing foregut were examined. RESULTS: Day 11 control fetuses showed normal separation of the respiratory primordium, with apoptotic bodies at the point of separation. A more caudal point of separation of the distal foregut without apoptotic bodies was found in 4 of 10 AMM fetuses. Day 13 AMM fetuses had dorsal or ventral outpouchings of the foregut, indicating which malformation they would develop. Abnormal branching of the notochord was seen from day 9.5 in AMM fetuses. This was not always associated with abnormal tracheoesophageal development. CONCLUSION: This study confirms that the abnormal observations made in the rat model apply to the mouse.