Experimental studies on rabbit tracheal homograft with 4, 8 and 12 tracheal rings in the upper, mid and lower portions of 108 healthy adult rabbits were performed, and changes in lumina of grafted trachea and repairing pattern of tracheal living cells were observed after 4, 8 and 12 weeks.
The following results and conclusion were obtained.
1. Luminal constriction of the grtfted trachea was noted in almost all cases with varing dimensions.
Approximately 21% decrease of the diameter was noted in the upper tracheal homograft group, and 39% in the lower one.
This constriction because to stabilize after 8 weeks in upper and midtracheal graft groups.
2. In groups with short tracheal ring graft, degree of luminal constriction was mild and epithelial repair more uniform with high percentage of transformation to columnar epithelium.
3. Epithelial regeneration was thought to arise from hyperplasia of the preserved basal cells, and in earlier stage the mucosa showed denudation and necrosis of columnar epithelium followed by single and／or stratified squamous metaplasia.
4. Epithelialization occurred broadly and early, in group of upper tracheal graft compared to lower ones.
5. 8 and 12 weeks after operation, varying kinds of intermixed covering epithelia were observed.
6. Ciliated columnar epithelium was not encountered in any case up to three months after grafting.
7. Transplanted tracheal epithelialization seemed to be influenced by metaplastic changes of host-tracheal mocosa.
8. Complete epithelialization occurred in the groups having received shorter lengths of graft.
9. Causes of death during the experiment were partly due to rejection phenomena, particularly in groups of lower part transplantation and of 12 rings transplants.
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