中华鳖肠道黏膜上皮细胞的超微结构

Ultrastructure of Mucosal Epithelium in Intestine of Soft-shelled Turtle,Trionyx sinensis

应用透射电镜技术,对15只正常中华鳖小肠和大肠黏膜上皮细胞的超微结构进行了研究。结果表明,中华鳖小肠黏膜上皮为单层柱状上皮,以高柱状吸收细胞为主,具有发达的微绒毛、线粒体、粗面内质网和膜包小囊泡,其结构的发达程度已接近高等哺乳动物和鸟类。吸收细胞之间可见少量低电子密度的亮细胞,其种类需进一步确定。杯状细胞明显可见,胞质内含大量黏液性颗粒,细胞游离面形成明显的微绒毛。内分泌细胞很少。大肠黏膜上皮细胞排列松散,全部由上下粗细不均的柱状细胞组成。大肠上皮内未见专门的杯状细胞,但上皮细胞顶部胞质内含大量黏液颗粒,细胞器分布于黏液颗粒团之下的胞质中。细胞间隙宽大明显,有利于黏膜免疫细胞出入上皮。小肠和大肠均未见腺体分布。

Ultrastructure of mucosal epithelium of small and large intestine in 15 Soft-shelled Turtles ,Trionyx sinensis ,was observed using transmission electron microscope. The results showed that the lumen of small intestine was lined by the simple columnar epithelium,most of the cells were high columnar absorbing ones with abundant developed microvilli. Oval nuclei situated near the cell base, There were many rod-shaped mitochondria,rough endoplasmic reticulum ,lysosomes and numerous vesicules within the absorbing cells. These structural characteristics were similar to the mammals and birds. On the other hand ,lower electron density cells occurred among the absorbing cells ,the nature of which needs to be further affirmed although the kinds of the organella within them wcre the same as other absorbing cells. Numerous goblet cells containing abundant mucigen granules interspersed among the columnar cells. Microvilli from free surface of some goblet cells appeared. In the large intestine,epithelium cells of mucous membrane loosely arranged and the interstructure spaces of the epithelium widely formed, which might help the movement of the intraepithelial lymphoeytes（IEL）. Mucigen granules accumulated in the upper part of the columnar cell ahhough there was not goblet in the large intestine, Intestine gland was not observed in the small and large intestine.