自体静脉移植后管壁超微结构的变化

目的　探讨自体静脉移植后内皮形态特征和中膜SMC增生特点 ,为静脉搭桥后再狭窄的防治提供资料。方法　兔 18只 ,随机分 6组 ,均作模拟血管搭桥手术 ,即将颈外静脉移植于颈总动脉 ,术后取材 ,光电镜观察。结果　移植后 1～ 4周管壁渐增厚 ,4～ 6周时达最厚 ,随后管壁不再继续增厚。对照侧静脉无微绒毛梭形内皮被移植段具有丰富微绒毛呈不同形态的内皮细胞所替代。移植后 1～ 2周 ,SMC肌丝和致密体减少 ,与合成和分泌有关的细胞器异常丰富 ,SMC从收缩型转变成合成型 ,四周时分泌型细胞器略有减少 ,但细胞间的胶原纤维明显增多。第 6～ 12周 ,SMC又渐从分泌型向收缩型转变。结论　自体静脉移植后 4～ 6周管壁厚度达高峰 ,内皮微绒毛增多。中膜SMC在 1～ 2周转型增殖最明显。提示术后 2周内是药物抑制SMC增殖的良机

Ultrastructural changes of endothelium and smooth muscle cell in rabbit autogenous vein graft

Objective To investigate the ultrastructural changes of endothelium and SMC proliferation in rabbit autogenous vein graft and provide the data for the prevention and treatment of restenosis.Methods The left external jugular vein of 18 rabbits(6 groups) were interposed between ipsolateral common carotid artery.Grafted veins were harvested at different time points postoperatively and observed under light and electron microscope.Results The grafted vein wall get gradually thicker.The wall thickness at the end of 4th week reaches the maximum.From then on,the thickness don′t continue to increase.The fusifrom ECs with little microvilli at control vein are replaced by various morphological ECs with rich microvilli in grafted veins. 1th～2rd week postoperatively,medial SMC contain little myofilament and dense body,but with rich sereting organells.These indicated that SMCs phenotype have changed from contractile phenotype to synthetic one.At the end of 4th week,secreting organells of SMC are less than that at 1st～2nd week but medial collagen fiber is getting much.From 6th～12th weeks.SMCs also gradually changed from synthetic phenotype to contractile one.Conclusions 4～6th week after autogenous grafting,the wall thickness is maximum,1th～2nd week after grafting the phenotype change and proliferation of medial SMC are the most apparent.much microvilli were seen.in grated vessels.The results suggested that in order to prevent and treat intimal hyperplasia,1th～2nd week postoperatively it is a better time for medicine to inhibit restenosis.