胎儿咽-食管肌层α-平滑肌肌动蛋白,肌球蛋白重链Ⅱ、Ⅲ表达的三维分布

Three-dimentional distribution of α-SMA,MHC-Ⅰ and MHC-Ⅱ in muscular layer of pharynx and esophagus in human fetus

目的:探讨胎儿咽、食管肌层中α-平滑肌肌动蛋白(α-smouth muscle actin,α-SMA)、肌球蛋白重链Ⅱ(myosin heary chain-Ⅱ、MHC-Ⅱ)、MHC-Ⅰ表达及其空间分布。方法:采用免疫组织化学SABC法及蛋白印迹法对20例胎儿咽、食管的α-SMA、MHC-Ⅰ、MHC-Ⅱ表达进行观察。结果:MHC-Ⅱ和MHC-Ⅰ共定位食管上、中段肌层,并主要表达在外部纵行肌,由上至下逐渐减少,至食管下段消失。而α-SMA则在食管上端内层肌开始表达,呈环行排列,由上至下逐渐增加,并由内肌层扩展到外肌层。结论:α-SMA、MHC-Ⅰ、MHC-Ⅱ共存于胎儿食管上中段,骨骼肌和平滑肌的移行呈渐进性,无明确界线。

Objective： To investigate the spatial distribution of α-SMA,MHC- Ⅰ and MHC-Ⅱ expression in the muscular layer of the human fetal pharynx and esophagus. Methods： A total of 20 human fetuses with an average age of 23 ± 4 weeks were used in this study. The pharynx and esophagus was collected from each fetus. Using anti-α-SMA, anti- MHC- Ⅰ and anti-MHC- Ⅱ antibodies, the specimens from 17 fetuses were prepared for histology and immunohistochemistry examination and those from other 3 fetuses for Western blotting analysis. Results： MHC- Ⅰ and MHC-Ⅱ were always co-localized and were dominant in the external longitudinal muscular layer, and gradually disappeared at the inferior end of the esophagus. In contrast, α-SMA expression was detected in the most inner muscular layer at the upper end of the esophagus and then gradually increased downward and outward. The muscle fibers expressing α-SMA were mainly circularly orientated. Conclusion： The results suggest that differentiation of the esophageal muscles proceeds from the superior to the inferior ends of the esophagus in the human fetus.