中华鳖肠道黏膜免疫相关细胞的形态学研究

MORPHOLOGICAL STUDIES ON CELLS INVOLVED IN MUCOSAL IMMUNITY OF THE INTESTINE IN THE CHINESE SOFT-SHELLED TURTLE

应用光镜和透射电镜技术,对中华鳖肠道黏膜免疫相关细胞的分布和结构进行了详细观察,并结合形态结构特点,对爬行动物黏膜免疫的特征进行了讨论。鳖肠道黏膜上皮细胞(尤其大肠段)排列较疏松,细胞间隙明显,上皮间隙内普遍分布着上皮内淋巴细胞(IEL)和浆细胞。IEL在上皮不同部位的分布比例为核下区∶核区∶核上区=4∶3∶3。核上区IEL以小淋巴细胞为主,而核区和核下区的IEI体积略大。淋巴细胞胞质内含有数个粗大的膜包颗粒。上皮内未见微皱褶细胞,IEL位于上皮细胞之间,并在上皮细胞之间伸出伪足。肠腔内有完整的游离淋巴细胞。肠道黏膜上皮间隙内的浆细胞一般位于核下区或核区,胞质内充满着扩张状态的粗面内质网。肠道固有膜散布着许多淋巴细胞(LPL)、浆细胞、巨噬细胞和一些白血细胞,以小肠段的分布最丰富。在有些肠绒毛内,LPL分布密集,几乎占据整个绒毛中心,但并未出现淋巴小结。固有膜浆细胞有两种形态:一种浆细胞的粗面内质网呈短的扩张状态,其数量占多数;另一种浆细胞的粗面内质网为板层状排列的扁囊状,数量较少。结果表明,参与中华鳖肠道黏膜免疫反应的细胞数量多,但黏膜上皮内缺乏微皱褶细胞(M细胞),固有膜中也不形成淋巴小结。提示爬行动物的黏膜免疫机理与哺乳动物和鸟类不尽相同。

By using microscopy and electron microscopy, morphological characteristics of cells involved in intestinal mucosal immunity in the Chinese soft-shelled turtle, Trionyx sinensis, were examined in detail, and, as a result, the nature of the mucosal immune response in the reptile was discussed. Epithelial cells in the intestinal mucosal arranged loosely along the intestinal mucosal membrane,especially in large intestine, and there were many obvious spaces between the epithelial cells. Intraepithelial lymphocytes （IEL） and plasma cells were widely distributed in the intestinal mucosal epithelium. The number ratio of the IEL in upper-nucleus region, nucleus region and lower-nucleus region of the epithelium was 4 ： 3 ： 3. In upper-nucleus region, small lymphocytes dominate while in nucleus and lower-nucleus regions, the volume of the lymphocyte becomes a little bigger and several large granules occurred in each cell. IELs located in spaces of the epithelium, some of which protrude pseudopods inside the epithelium and some were seen in the lumen of the intestine. In the nucleus region and lower-nucleus region of the epithelium, there were many plasma cells locating between the epithelial cells,in which the dilated rough endoplasmic reticulum were filled up. Lamina propria lymphocytes （LPLs） ,plasma cells, macrophages, and some leucocytes dispersed in the lamina propria. In intestinal villi, the lymph nodule was not observed although LPLs sometimes dominated the villi. The structure of the LPL was generally like that of IEL. In the lamina propria, there were two types of plasma cells, one has the dilated rough endoplasmic reticulum and the other does the parallel one, and the former type dominate in number. The results sugested that the mucosal immune reaction mechanic of the reptile was different in some ways from the mammalian and bird which have M cells in the epithelium and lymph nodules in the lamina propria.