Abstract
Forty-four aortas dissected from human subjects were sliced into 30-50 se rial sections and studied morphologically for the presence of thrombi. A total of 569 thrombi were found histologically in 1,400 sections. The frequency of thrombosis was 7% for subjects under 30 years-old. However, with increasing age, the frequency rose to 8% in the third decade, 9% in the fourth decade, 13.5% in the fifth decade, 10.5% in sixth decade, 25.5% in the seventh decade and 33.5% for subjects over 80 years-old.
Thrombi were morphologically classified into three types: (1) microthrombi (2) membranous thrombi, and (3) large massive thrombi. The latter were rarely found on the intima, and no sclerotic lesions were observed.
The frequency of thrombosis on non-pathologic areas was 11 %, and almost all of them were microthrombi. The thrombi on the areas of cloudy thickening was 47% with 6% of them being classified as membranous thrombi or large massive thrombi. The thrombi on atherosclerotic lesions was 42%, unusually high compared with the other categories and 32 % of them were membranous or large massive thrombi.
In each region of thoracic and abdominal aorta, thrombi were apt to be more on abdominal aorta than that on thoracic aorta.