抄録
Intima cushion obstructing the lumen of small pulmonary arteries of the fetus and newborn was studied histologically on the lungs of 314 autopsy cases, less than 6 months of age. Together with these, 31 fetuses were also examined. The results are as follows: 1. The intima cushion develops in the later stage of intrauterine life and is encountered most frequently at the perinatal period. It begins the involution immediately after birth. The oldest case with the cushion was 8 days of age. 2. The intima cushion is composed of the overgrowth of immature media muscle cells protruding into the vascular lumen, which becomes subsequently flattened and disappears physiologically after birth with dilatation of the arterial lumen due to increased pulmonary blood flow. 3. The intima cushion may regulate the fetal pulmonary circulation by way of blocking the blood stream to alveolar capillaries, whereas, it should impede the pulmonary circulation, if it remains still after the birth. 4. Massive aspiration of amniotic fluid in perinatal period may cause the persistence of intima cushion which aggravates the pulmonary circulation. Retardation of amniotic fluid absorption, pulmonary edema, exudation and alveolar hemorrhage due to anoxia may be superimposed on this condition. 5. The intima cushion is not a vascular anomaly and no relationship is established between this structure and the cardiac anomalies.
https://ror.org/058548196 
