American Journal of Obstetrics and Gynecology vol:191 issue:3 pages:830-6
OBJECTIVE: This study was undertaken to evaluate the effects on peripheric pulmonary vessel muscularization by tracheal occlusion (TO) performed at different gestational ages in fetal rabbits with surgically induced diaphragmatic hernia. STUDY DESIGN: In 23 New Zealand white does, both ovarian end fetuses underwent surgical creation of diaphragmatic hernia at 23 days of gestation (pseudoglandular phase). At 26, 27, or 28 days 1 fetus underwent TO, the contralateral one underwent a sham operation for a total of 46 fetuses. At 30 days (alveolar phase), fetuses were harvested together with 1 nonoperated internal control. Lungs were processed for vascular morphometry. Proportionate medial thickness and muscularization of intra-acinar vessels were evaluated. RESULTS: Late TO (day 28; saccular phase) normalizes the lung-to-body weight ratio and causes significant medial thinning in vessels up to 35 microm diameter. CONCLUSION: Tracheal occlusion decreases muscularization of intra-acinar pulmonary vessels in a gestational age-dependent fashion, with maximal effect when TO is performed at 28 days.