since macrophages and macrophage-derived factors have been found to promote synthesis of bm collagen type iv , and since transitional and interstitial areas are rich in macrophages and histiocytes , respectively , it is suggested that these mononuclear cells and the factors secreted by them play a significant role in the thickening of the bm of pcv and capillaries in ra synovitis .
C0004799
bm
C0009333
collagen type iv