The development of the proximal oesophageal pouch in the adriamycin rat model of oesophageal atresia with tracheo-oesophageal fistula

This study examined the morphological development of the proximal oesophagus in the Adriamycin-induced rat model of oesophageal atresia. The proximal oesophageal segment in oesophageal atresia with tracheo-oesophageal fistula (OA\TOF) has been assumed to be of similar embryological origin to the distal oesophagus. However, recent research using the Adriamycin model of OA\TOF has indicated that these structures may have a different origin. Time-mated Sprague-Dawley rats were administered either Adriamycin intraperitoneally or saline of an equivalent volume between days 6–9 of gestation. The rats were sacrificed between days 11–19 of gestation, their embryos removed and histologically sectioned. These sections were analysed to observe the morphological changes occurring in the proximal foregut. The proximal oesophageal pouch first appeared on day 15.25 as a dorsal outpouching of the proximal foregut immediately cranial to an area of apoptosis in the dorsal epithelium of the distal pharynx. It elongated through a process of cellular proliferation until it was clearly formed on day 16. Relatively little growth occurred from days 17–19. In the rat developing oesophageal atresia, the proximal oesophageal pouch has an origin different to that of the distal oesophagus. This study may explain the difference in immunohistological properties and intrinsic nervous supply between the proximal and distal oesophageal segments in oesophageal atresia.