ULTRASTRUCTURAL AND HISTOCHEMICAL FEATURES OF THE GROUND SUBSTANCE INCYCLOSPORINE-A-INDUCED GINGIVAL OVERGROWTH

THE OVERGROWTH-AFFECTED GINGIVA Of patients treated with cyclosporin A after kidney transplant was examined with ultrastructural and histoch emical methods to evaluate the involvement of connective tissue. Gingi val overgrowth has the same clinical signs as local edema. The ultrast ructural study showed that the dimensional increase was largely due to increased production of amorphous ground substance by fibroblasts, po ssibly resulting from an increased release of histamine by mast cells. The histochemical data revealed that the affected tissues contained h igher levels of glycosaminoglycans and that cyclosporin A induced comp arably high levels of glycosaminoglycans in in vitro cultures of fibro blasts obtained from normal gingiva. The combination of ultrastructura l and histochemical data, therefore, strongly suggests that the respon se of the connective tissue in gingival overgrowth cannot be ignored a nd may be the main cause of the observed pathological condition.