Histometrical Investigation of Pulmonary Vascular System in Experimental Diaphragmatic Hernia

Diaphragmatic hernia was experimentally produced in fetal rabbits from the 21st to 25th gestational day by rupturing the left diaphragm in utero. The pulmonary vascular system of 18 out of 48 fetuses successfully recovered was examined. Radius and thickness of the media of the pulmonary artery were measured using Suwa's histometrical techniques. Total length of the acinar arteries and capillaries were measured by a stereological method. The radius of the pulmonary acinar arteries in the experimental models was smaller than normal. The proportion of the thickness of the media to the radius increased significantly in the models, and the total length of the acinar arteries as well as capillaries was remarkably reduced in the models. These findings were all in the bilateral lungs. These results suggest that pulmonary vascular disorders caused by diaphragmatic hernia in fetal life result in absolute reduction of total pulmonary vascular capacity.