镜下主动脉切面中的红色血块表示缩小的主动脉夹层。由于主动脉剥离所致，主动脉剥离时，血液在压力下从内膜向外穿透肌层到达外膜。
This microscopic cross section of the aorta demonstrates a red blood clot that is compressing the aortic lumen. This occurred as a result of aortic dissection in which there was a tear in the intima followed by dissection of blood at high pressure out through the muscular wall to the adventitia. This blood dissecting out can lead to sudden death from hemothorax.