双重染色显示Cajal细胞和NOS神经在胎儿小肠肌间神经丛的分布

目的研究Cajal细胞与NOS神经在胎儿小肠肌间神经丛的分布模式.方法采用18～26周龄胎儿小肠全层铺片和冰冻切片的NADPH-黄递酶(NADPH-d)组织化学法和c-kit免疫细胞化学双重染色.结果胎儿肌间神经丛周围Cajal细胞体为梭形或卵圆形,核周胞质较少,常见2～3个细长的突起,彼此间形成完整的独立细胞网络.NOS阳性神经广泛分布于小肠的肌间神经丛和环肌内,其中,以肌间神经丛最为丰富,构成神经节、节间束及三级神经纤维网的主要神经成分.肌间神经节内的NOS阳性神经元轮廓较清晰,多数为DogielⅠ型神经元,成簇密集分布,每个神经节内含有数个至数10个NOS阳性神经元.NADPH-d和c-kit免疫细胞化学双重染色未发现NOS阳性神经和Cajal细胞有共存现象,但NOS阳性神经纤维的走行与Cajal细胞及突起间的距离较近.结论本研究结果提示在胚胎发育中晚期,肌间神经丛的抑制性神经递质NO可能已具备对Cajal细胞及胃肠平滑肌调控的结构基础.

Distribution of NOS nerves and interstitial cells of Cajal in myenteric plexus of human fetal intestine

Objective To investigate the distribution modes of NOS nerves and interstitial cells of Cajal (ICCs) in myenteric plexus of human fetal intestine. Methods Small intestine samples from 12 fetuses were collected for the preparation of whole mount preparations and cryo sections examined by immunocytochemistry for c kit receptor tyrosine kinase and histochemistry for NADPH diaphorase. Results ICCs associated with the myenteric plexus in the fetal small intestine were observed in the shape of spindle or ovoid with two to three slender processes forming an independent and complete cellular network. While NOS positive nerves, which constitute the main neuronal component of ganglia, connecting strands, and nerve fibers, were found within the circular muscle layer and myenteric plexus of the small intestine and the latter was especially rich of this kind of nerves. Most of these positive neurons were Dogiel I type neurons and they often gathered in cluster in the ganglia. Each ganglion contained several to dozens of NOS positive neurons. Although no colocalization of ICCs and NOS positive nerves was found by double staining of whole mount preparations and cryo sections, they were closely distributed. Conclusion Our results indicate that NO released by myenteric plexus, an inhibitory neurotransmitter, may possess the function of regulating ICCs and smooth muscle in late stage of the fetus.