Morphological and morphometrical analysis of schistosomal granuloma degradation

In vivo degradation of the extracellular matrix of Schistosoma mansoni granulomas was morphologically studied by light and electron microscopy using 60 day-infected hepatic isolated and acellular granulomas (aPMC) which had been implanted into the subcutaneous tissue of syngenic albino mice and examined 4, 15, 20, 30 and 40 days after implantation. The progressive changes of aPMCs were estimated by measurements of aPMCs surface (micron2) on paraffin sections. After implantation, polymorphonuclear leukocytes were the initial population recruited whereas macrophages and fibroblasts were prominent in the late stages. Eosinophil leukocytes and in a lesser extent, mast cells increased in number. In electron microscopy, progressive disappearance of extracellular matrix and some modified collagen fibrils either in extracellular or intracellular localization represented matricial changes. The morphometrical analysis of aPMCs of the surface (micron2) after implantation showed a significant reduction of aPMCs (p < 0.001) in all stages after implantation. Polymorphonuclear cells, macrophages and fibroblasts seemed to be the major responsible cells involved in aPMCs resorption.