胎儿消化道Cajal间质细胞超微结构研究

Ultra-Structural Features of Interstitial Cells of Cajal in Fetal Enteron

目的研究胎儿消化道Cajal间质细胞(interstitial cells of cajal,ICC)超微结构并对其分类.方法搜集流产及早产死胎胎儿标本(妊娠18、28周各1例),采用硝酸铅、醋酸铀染色,JEM-2000EX透射电子显微镜观察.结果 1.ICC在电镜下呈现巨大卵圆形核,核周胞浆少,2～5个长分支细胞突起使其呈纺锤状或卫星样细胞;2.ICC超微结构随消化道不同部位而异.食管、胃、十二指肠、空肠、回肠ICC可见膜内陷小泡、粗面内质网,线粒体,高尔基复合体ICC致密体、脂滴,异染色质,但粗面内质网,线粒体,高尔基复合体,不如大肠各段丰富成熟;位于阑尾、升结肠、横结肠、降结肠、乙状结肠、直肠ICC超微结构相似,ICC具有发育良好粗面内质网,丰富线粒体常紧密排列在胞质中;有膜内陷小泡,可见高尔基复合体、致密体、脂滴,大量异染色质沿核膜下分布,结构清晰;3.依据组织层面不同ICC超微结构有差别:消化道各段纵肌间、肌间神经丛周围ICC为多个足突的星形细胞;环肌间ICC、平行环肌分布,为2个足突梭形细胞;4.ICC之间,ICC与神经细胞、平滑肌细胞均存在'似缝隙连接'为本组标本中主要连接形式.结论胎儿ICC超微结构随分布位置而异,组织层面不同ICC结构存在差异.同一胎龄纵肌和肌间神经丛周围ICC超微结构较环肌间ICC丰富成熟.随胎龄增加,ICC超微结构渐成熟.ICC与其他ICC、神经细胞、平滑肌细胞间'似缝隙连接'对ICC功能发挥具有重要作用.

Objective To study the ultra-structural features of interstitial cajal cells (ICC)in fetal enteron and then classify them.Methods Ultra-structural features of ICC in fetal enteron with spontaneous abortion or premature birth were detected under JEM-2000EX transmission electron microscope for the cause of fetal death, including two fetus specimens of a gestation 18 months and 28 months stained with lead nitrate and uranium acetate.Results ICC had a big oval karyon and a little of cytoplasm. ICC formed spindle or stellate cells with 2 to 5 long cell processes . From the esophagus to the terminal ileum ICC mostly had the same ultra-structural features, but with mitochondria and a well-developed endoplasmic reticulum and Golgi complex in the whole colon and the rectum , more than those of esophagus and small intestine. In the whole colon and rectum ICC had similar ultra-structural features. ICC also possessed an abundance of mitochondria and a well-developed endoplasmic reticulum and Golgi complex. ICC also possessed Caveloae lipid droplet with more electron dense and heterochromatin. Two types of ICC were identified under JEM-2000EX transmission electron microscope. One type was present from the esophagus to the terminal ileum and the other type was observed in the colon and rectum. The first type ICC in circular muscle layer was bipolar cells which extended to tapering processes in opposite directions. These processes rarely branched, and their appearance was similar to smooth muscle cells.Most of them ran parallel to the circular muscles . The second type of ICC in the myenteric plexus and longitudinal muscle layer was mostly multipolar and rarely bipolar cells with long processes. They showed an irregular appearance characterized by numerous short spike-like branches. Processes of multipolar cells extended in every direction and connected with each other. ICC nerve cells and smooth muscle cells were connected with gap-like junction, which was the main connection mode .Conclusions The ultra-structural features of ICC in fetal enteron varied with the diffe-rent locus and different tissue sheets in the enteron. The mitochondria and a well-developed endoplasmic reticulum and Golgi complex of the whole colon and rectum are more and more developed than that of esophagus and small intestine. Ultra-structural features of ICC will develop further with the gestational age. The gap- like junction among ICC nerve cell and smooth muscle cell are highly important for ICC to educe function.