Pathological Study on Organization of Thrombi in Human Aorta

Abstract

Large number of thrombus were frequently found on intimal surface of the aortas obtained from autopsy cases. Thrombi were classified morphologically into three types-microthrombus, membranous thrombus and massive thrombus as shown in our previous study.
Organizing processes of each thrombi were discussed on this paper.
1) Microthrombi could be found not only on sclerotic intima but also on no lesion areas. Many of them could be thought to be dissolved if they exist longer on living aortas. However, some of the microthrombi showed certainly the transformation into microfibrous elevations. The main cells that participated in organization of microthrombus were endothelial cells.
2) Membranous thrombi were apt to be deposited on sclerotic lesions. Unlike other types of thrombus, cellular reactions were minimum in organizing processes. The organization of these thrombi resulted in hyaline thickening of intima.
3) Massive thrombi could be found frequently on atheromatous plaques or ulcerative lesions. Their organization showed dual processes; the organizations from superficial layer and from base of thrombi. The organization from superficial layer of thrombi seemed to be more important.
Smooth muscle-like cells seen in superficial layer of organizing thrombus were thought to play important role in organizing processes.
The authors could not be determined whether the origin of these cells were endothelial, multipotential mesenchymal cells or from blood cells.