OBJECTIVETo detect the factors relevant to stenosis of tracheal graft and to find feasible methods to solve this problem.

METHODSSixteen mongrel dogs were divided into groups A and B randomly and equally. Five-ring-length tracheal segments were allotransplanted. All grafts and anastomotic sites were covered with omental pedicles. In group A, no immunosuppressant was given and in group B, the recipients were treated with cyclosporine. The animals were sacrificed 4 weeks after operation, and their postmortem specimens were examined grossly and histologically. All allografts were assessed by percent patency. Epithelial regeneration and morphology of the cartilage were semiquantitatively evaluated.

RESULTSStructural integrity of the allografts were maintained better in group B than in group A. Tracheal stenosis was found to be more serious in group A. The scores of epithelial regeneration and cartilage morphology were higher in group B than in group A, and in each group positive correlation was found between the percent patency and the score of epithelial regeneration or cartilage morphology.

CONCLUSIONSImmunosuppressive drugs are necessary to maintain the structure of allografts. Tracheal stenosis is correlated closely with epithelial regeneration and morphological maintenance of the cartilage.