兰州鲇与鲇消化系统的形态学及组织学比较研究

为探究黄河濒危鱼类兰州鲇（Silurus lanzhouensis）消化系统的形态学和组织学结构特点，以鲇（Silurus asotus）为对照，对兰州鲇消化系统形态学和组织学进行了深入研究。结果表明:（1）兰州鲇与鲇的消化道和消化腺形态相似，具有肉食性鱼类的特征。兰州鲇消化道较短，有发达的“U”型胃，胃内皱褶明显，无幽门盲囊，肠道短且粗，可分为前肠、中肠和后肠三部分，前肠粗大，后肠较细。两种鲇属鱼类都有独立致密的肝脏和胰脏。（2）兰州鲇的比肠长显著大于鲇（P < 0.05），比胃重、比肝胰脏重显著低于鲇（P < 0.05），但二者的比肠重无显著性差异（P>0.05）。（3）兰州鲇胃的皱襞幅度小于鲇，且环肌层比兰州鲇薄。兰州鲇与鲇前肠的肠黏膜均形成了大量皱襞，肠黏膜、褶皱粗大，但鲇的褶皱分支较细密。兰州鲇与鲇的后肠与前肠相比，肠腔变小，褶皱数量明显减少，高度降低。黏膜层分布有杯状细胞和柱状细胞。兰州鲇与鲇的肝脏肝小叶间缺少结缔组织，分界不明显，而兰州鲇肝细胞的密度大于鲇。综上所述，兰州鲇与鲇的消化系统相似，均符合肉食性鱼类消化系统特征，结合消化生理等研究结果，表明兰州鲇的消化能力弱于鲇，这可能是在自然情况下兰州鲇的分布区域及适应性不及鲇的原因之一。

COMPARATIVE STUDY ON MORPHOLOGY AND HISTOLOGY OF DIGESTIVE SYSTEM OF SILURUSLANZHOUENSIS AND CATFISH (SILURUSASOTUS)

To investigate the characters of the digestive system structure of Silurus lanzhouensis and enrich its refe-rence information, a comparatively research on the morphology and histology of digestive system between Silurus lan-zhouensis and catfish (Silurus. asotus) was performed. The results showed:1. The morphology of digestive tract and di-gestive gland of Silurus lanzhouensis was similar with those of catfish (Silurus asotus), which was characterized as car-nivorous fish, suggesting the shorter digestive tract and stronger“U”type stomach. Besides, pyloric caecum was not found. They both had short and thick gut in which foregut was thicker than hindgut. The liver and pancreas in the both species were observed to be independent and pyknotic. 2. The higher relative gut length (RGL), the lower hepatosoma-tic index (HSI) and stomach index (STI) was found in Silurus lanzhouensis, compared with those of catfish (S. asotus) (P<0.05). There was no significant difference observed in the gut index (GI) between the both two species (P>0.05). 3. The larger fold amplitude and the thicker circular muscle layer were found in the stomach of catfish (Silurus asotus) in comparison with that in Silurus lanzhouensis. The numerous plica and the strong mucosal folds was found in the fore-gut of both two species, although those in catfish (Silurus asotus) was denser. The gut diameter, the number and height of fold was decreasing from foregut to hindgut. The goblet cells and columnar cells were distributed on the mucous membrane layer. In the hepatopancreas of the both species, the lack of connective tissue between the hepatic lobule led to the unconspicuous dividing line. Moreover, the density of hepatocyte was larger in Silurus lanzhouensis than that in catfish (Silurus asotus). Overall, Silurus lanzhouensis had the similar digestive system with catfish (Silurus asotus), which was characterized as carnivorous fish, but the digestive ability of Silurus lanzhouensis was weaker. It might be one of the reason why Silurus lanzhouensis had the narrower distribution and weaker adaptability than catfish (Silurus asotus).