| Abstract: | The development of the avascular fibrous capsule which surrounds free floating intraperitoneal blood clots in mice and rabbits is described. In mice, the capsule at 2 wk consisted of an outer layer of partially flattened macrophage-like cells overlying a thick layer of myofibroblasts embedded in a collagenous stroma. In contrast, in rabbits the capsule at 2 wk consisted of 3 distinct layers: an outer layer of mesothelial cells; an underlying relatively acellular layer containing a few macrophages; and, immediately adjacent to the clot, an innermost layer of variable thickness consisting mostly of myofibroblasts. The myofibroblasts of the rabbit capsule were fewer in number than those of the mouse. Detailed examination of the formation of these capsules suggests that myofibroblasts may develop from cells within the peritoneal cavity that show morphological features characteristic of monocytes/macrophages. |
