Collagen arrangement in hepatic granuloma in mice infected with Schistosoma mansoni: dependence on fiber radiation centers

The collagen structure of isolated and in situ liver granuloma from Swiss W ebster mice infected with Schistosoma mansoni was sequentially and three-di mensionally analyzed during different times of infection (early acute, acut e, transitional acute-chronic, and chronic phases) by laser scanning confoc al microscopy and electron scanning variable vacuum microscopy. The initial granuloma structure is characterized by vascular collagen residues and by anchorage points (or fiber radiation centers), from where collagenous fiber s are angularly shed and self-assembled. During the exudative-productive st age, the self-assembly of these fibers minimizes energy and mass through co ntinuous tension and focal compression. The curvature or angles between col lagen fibers probably depends on the fibroblastic or myofibroblastic organi zation of stress fibers. Gradually, the loose unstable lattice of the exuda tive-productive stage transforms into a highly packed and stable architectu re as a result of progressive compactness. The three-dimensional architectu re of granulomas provides increased tissue integrity, efficient distributio n of soluble compounds and a haptotactic background to the cells.