油红O染色显示肺小动脉内的脂肪球。小球染成红橙色。许多这些小球在整个肺部的累积效应类似于大的肺栓塞，在发生后2至3天出现呼吸困难，可见于骨折的钝性创伤。
An Oil Red O stain demostrates the fat globules within the pulmonary arterioles. The globules stain reddish-orange. The cumulative effect of many of these gobules throughout the lungs is similar to a large pulmonary embolus, but the onset of dyspnea is usually 2 to 3 days following the initiating event, such as blunt trauma with bone fractures.