肺血减少肺动脉低压时肺小血管的病理形态观察和分析

Pathological features of pulmonary arteries in a porcine model of cyanotic congenital heart defect with decreased pulmonary blood flow

目的建立紫绀型肺血少动物模型,对肺血减少时未成熟肺小血管进行形态观察和半定量分析,观察肺血减少时未成熟肺小血管的发育特点。方法取紫绀型肺血少动物肺组织,进行固定、制片及染色。光镜和透射电镜观察,形态半定量测量分析肺小动脉中膜厚度(media thickness,MT)及中膜厚度百分比(percentage of media thickness,MT%)、中膜面积(media section area,MS)及中膜面积百分比(percentage of media section area,MS%);计数单位面积肺小动脉数目(arterial numbers of per square centimeter,APSC)和单位面积肺泡数量(mean alveolar nunber,MAN);计算同一张切片所有泡内肺动脉(intraacinar pulmonary arteries,IAPA)中肌型动脉(circular muscular artery,CMA)、部分肌型动脉(partially muscular artery,PMA)和无肌型动脉(non-muscular artery,NMA)的比例。结果同对照组(C组)相比,光镜观察肺血减少组(D组)肺小动脉中层退化和发育不良,管腔扩大,形态不规则,管壁厚薄不均,部分弹力纤维层中断、缺失。PMA和NMA比例较C组高,而CMA比例相对较低(P<0.001)。D组肺小动脉MT、MT%及MS、MS%均显著小于C组(P均<0.001)。D组APSC较C组减少(P<0.01),而MAN与C组差异无显著性(P>0.05)。电镜下显示D组肺小血管内皮细胞胞质肿胀,基膜变薄;弹力纤维排列不整齐,有的区域萎缩变薄或中断;血管中层平滑肌轻度萎缩;细胞器减少,线粒体空泡化;部分肺泡Ⅱ型上皮细胞增生明显,板层体丰富。结论肺血流减少时肺小血管发育不良或退化,形态结构异常影响器官的正常功能,尽早改善肺血少状态是促进肺血管发育和改善全身状况的关键。

Purpose Using quantitative morphometric techniques, To analyzse the developmental characteristics of pulmonary arterial and alveolar with a porcine model of cyanotic congenital heart defect with decreased pulmonary blood flow that we had established. Methods Lung biopsy specimens were taken from animals of control （ C） and cyanosis （ D） groups and than sectioned and stained. The morphological observation and the method of half-quantitative morphometric technique were applied to measure the following char-acteristics：the media thickness （ MT） and the percentage of media thickness （ MT%） , the media section area （ MS%） and the per-centage of media section area （ MS） , the numbers of micro-arteries per square centimeter （ APSC） . In addition, we calculated the ratio of CMA, PMA and NMA in the same section of lung biopsy specimens. Results There showed universally distended, irregular and thin-walled vessels in the lung biopsy specimens of group D under the light microscope. There was an increased number of pulmonary arteries whose media were hypoplastic. The MT, MT% and MS, MS% in group D were significantly less than those of group C （ all P〈0. 001）, the APSC was also less in group D than in group C （P〈0. 01）, but MAN were not significantly different between two groups （P〉0. 05）. Electron microscopy revealed endothelial swell and irregularity, a thinned basement membrane, a disorganized or disrupted elastic fibers layer. The smooth muscle of vascular media shrunk. In addition to these, other changes included the mitochon-drion vacuolization, a diminished cellular organelle and type Ⅱ alveolar epithelial hyperplasia. Conclusion The pulmonary vessels are evidently hypoplastic or degenerated in cyanotic congenital heart defect with decreased pulmonary blood flow, and the function is thought to be influenced by the morphological changes. To promote the pulmonary artery growth and improve this pathophysiological state, it is critical to increase the pulmonary blood flow.