Abstract
We performed lightmicroscopic and electron-microscopic observation on pulmonary arterial walls in thrombosis of pulmonary arterial stem. In the arterial wall attached with thrombus, marked arteriosclerotic changes could be seen, that is, we could observe the prolifiration of elastic and collagen fibers in the intimal layer, fragmentation and destruction of internal elastic lamina and degeneration and atrophy of smooth muscle cells in tunica media. In pulmonary arterial tree the mechanical destruction of intimal layer and insudation of blood elements were confirmed throughout the peripheral small arteries and arterioles. It was difficult to observe these changes because of associated early organization of thrombus in the arterial stem, but in some cases we could confirm these changes and prove that these changes were greatest in pulmonary arterial tree. In conclusion totality of hemodynamic load due to pulmonary circulatory derangement in the periphery rebounded to the pulmonary arterial stem, and it caused destruction and insudation in the intima at the arterial stem. Consequently these arterial changes induced the thrombus formation in the pulmonary arterial stem.
