Lung development following diaphragmatic hernia in the fetal rabbit

Diaphragmatic hernia was created in 39 rabbit fetuses on day 23 of gestatio n, Fifteen fetuses underwent a sham thoracotomy (SHAM). Thirty-nine non-ope rated littermates served as internal controls (CTR), Fetuses were harvested by Caesarean section on days 25, 27, 29 and 30 of gestation. Pulmonary res ponse was evaluated by lung to body weight ratio (LBWR), morphometry, and d ensity of type II pneumocytes, No difference was found between CTR and SHAM fetuses at term, CDH fetuses had smaller lungs (LBWR 0.014 +/- 0.004 versu s 0.030 +/- 0.04 in CTR, P < 0.0001), a less complex acinus [mean terminal bronchial density (MTBD) 1.786 +/- 0.408 versus 0.917 +/- 0.188, P < 0.0001 ], thicker alveolar septa [mean wall transection length (LMW) 0.0221 +/- 0. 008 versus 0.0142 +/- 0.002, P = 0.0003], and a lower type II cell count (1 44.5 +/- 19.33 versus 216.2 +/- 27.85 per high power field, P < 0.0001). Th e differences in MTBD and LMW were significant from gestational day 25 onwa rds, and the differences in type II, cell count from day 27 onwards, Surgic al diaphragmatic hernia in rabbit fetuses in the late pseudoglandular phase reproduces many features of the pulmonary hypoplasia associated with human congenital diaphragmatic hernia, including the delayed maturation. The eff ects are present within 2 days following experimental diaphragmatic hernia and progress over time.