Reaction of the Subcutaneous Tissue of Rats to Injected Air

Single discrete gas pockets were formed by injection of air into the dorsal subcutaneous tissue of rats. The presence of the gas caused a local morphological reorganization which was complete in 2 weeks. A wall, consisting mainly of modified fibroblasts and collagen fibers, developed around the gas and local vasculature increased in proportion to the wall thickness. After removal of the gas, opposing surfaces of the wall fused together and the collagen fibers with their associated cells were resorbed. Enlarged blood vessels remained after the other modified structures were no longer present in the pocket wall.