[Experimental congenital diaphragmatic hernia with pulmonary hypoplasia in a rat model]

Aiming at better understanding the mechanisms of malformation and the pathophysiology of congenital diaphragmatic hernia (CDH) and the pulmonary hypoplasia (PH) associated to it we have developed an experimental model in the Wistar rat fetus according to the following design: Three time-dated pregnant rats had 1 ml of olive oil instilled into the stomach at the 9 1/2 day of gestation (control group) and six more were treated with 115 mg/kg of Nitrofen in olive oil (experimental group). After Cesarean section on the 21st day we recovered 29 normal fetuses from the control and 41 fetuses from the experimental groups. Seventeen of these did not have diaphragmatic defects whereas the remaining 24 had left CDH. Fetuses from treated rats were significantly smaller than control ones and those bearing CDH were even smaller than their littermates. Total wet lung weight was significantly smaller in both subgroups of the experimental group. Histologic studies revealed that: 1) There were some variations in the degree of pulmonary hypoplasia in fetuses with CDH probably related to the size of the defect. 2) The main differences in maturation between lungs in control and experimental groups were in the tubulo-acinar structure. We describe the ultrastructure in both groups. This study recalls that some teratogens may be implicated in the pathogenesis of CDH, and also that PH, which was also present in treated fetuses without CDH, could be the cause rather than the consequence of CDH. In that case, our current therapeutic aims should be reviewed.