Abnormalities of the tracheal cartilage in the rat fetus with tracheo-oesophageal fistula or tracheal agenesis

Many infants with oesophageal atresia and tracheo-oesophageal fistula (OA/T OF) have associated tracheomalacia (TM), which is one of the reasons for re spiratory complications after surgical correction of the atresia. OA/TOF wa s induced in the offspring of pregnant rats by intraperitoneal injection of adriamycin. Fetuses were harvested by caesarean section. The trachea, oeso phagus, lungs, and stomach were removed en bloc and stained for cartilage u sing Alcian blue. The tracheas were examined, photographed, and relevant pa rameters pertaining to the tracheal cartilage were measured. Exposure to ad riamycin resulted in a range of anatomical defects including OA/TOF (47%) a nd tracheal agenesis (TA) (41%). Adriamycin-treated fetuses were smaller (P < 0.01), yet had longer tracheas (P < 0.001) than control fetuses. The OA/ TOF fetuses had more tracheal cartilage rings than controls (P < 0.01), whe reas TA fetuses had fewer(P : 0.001). Both OA/TOF and TA fetuses had more m alformed tracheal cartilage rings than controls (P < 0.001 and P < 0.05, re spectively). Cartilage in the proximal part of the trachea was most frequen tly and severely affected (P < 0.05). These observations clarify the struct ural abnormalities of tracheal cartilage that occur in rat fetuses with OA/ TOF or TA induced by adriamycin, and may explain the functional disturbance s of TM seen in OA/TOF.