Esophageal atresia with tracheoesophageal fistula: Suggested mechanism in faulty organogenesis

Background/Purpose:The organogenesis of esophageal atresia with tracheoesop hageal fistula (EA-TEF) is unknown; Using an established model for EA-TEF i n rats, the authors proposed to study this aberrancy of development in the hope of gaining insight into its mechanism of formation. Methods: Pregnant Sprague-Dawley rats were injected with 2.2 mg/kg of Adria mycin intraperitoneally on days 6 through 9 of gestation. Using microdissec tion, the trachea, blind-ending esophagus, TEF, and stomach were isolated f rom embryos of various gestional ages. The specimens were analyzed histolog ically with routine H&E staining. Results: The classic EA-TEF developed in the embryos, with proximal EA and distal TEF. As expected, the atresia formed as a blind-ending pouch, but th e distal fistula began as an apparent equal trifurcation of the tracheal an lage into two mainstem bronchi and the fistula tract leading to the stomach . Histological analysis of the fistula tract showed respiratorylike pseudos tratified columnar epithelium. Conclusions: TEF develops as the middle branch of a tracheal trifurcation. EA-TEF occurs by a primary atresia of the esophagus. As a secondary phenome non, the distal foregut anlage is switched toward the pulmonary phenotype. It trifurcates, and its middle branch grows caudally to fistulize into the stomach. J Pediatr Surg 34:204-208. Copyright (C) 1999 by W.B. Saunders Com pany.