马口鱼消化道的形态及组织学结构特征

为了解马口鱼消化道的形态结构特点, 采用解剖学、石蜡切片-显微技术及扫描电镜技术观察研究了马口鱼消化道的形态及组织学结构特征. 结果显示: 马口鱼消化道由口咽腔、食道、肠道组成, 无胃; 口咽腔无颌齿, 具咽齿; 舌短小, 被覆复层扁平上皮, 具少量味蕾及较多圆形粘液细胞. 食道及肠道均由粘膜层、粘膜下层、肌层及外膜构成. 食道粘膜层主要由复层扁平上皮构成, 杯状细胞较多, 肌层发达, 内层环肌、外层纵肌. 肠道分前、中、后三段, 呈“S”形盘曲, 肠长指数0.86~1.50; 肠内面皱褶发达, 粘膜上皮为单层柱状上皮, 其游离面有微绒毛密集排列形成的纹状缘, 后肠微绒毛密集程度略小于前中肠; 上皮细胞间分布有杯状细胞, 杯状细胞的数量前、中肠较多, 后肠后段较少, 肠管直径、肠绒毛数量及其高度由前到后渐减. 马口鱼消化道的结构特征与其肉食性相适应.

Morphological and Histological Structural Feature of Digestive Tract in Opsariichthys bidens

In order to study the morphological and histological features of the digestive tract in Opsariichthys bidens, we observed the structure of the digestive tract using methods of anatomy, paraffin secyion- photomicrography and scanning electron microscope. The results show that the digestive tract is composed of orol-pharyngeal cavity, esophagus and intestines, but without stomach. There is no jaw teeth found, but instead pharyngeal teeth in orol-pharyngeal cavity. A small number of taste buds and a large number of mucous cells are identified in stratified squamous epithelium on short tongue. The esophagus and intestine consist of mucous membrane layer, submucosa, muscular and the outer membrane. The mucous membrane of the esophagus with numerous mucous cells is composed of the stratified squamous epithelium cells. The thick muscle layer is composed of ring muscle and longitudinal muscle. The bent ‘S’-shaped intestine can be divided into foregut, midgut and hindgut. The intestine index is 0.86-1.50. Well-developed plica is present in the internal wall of the bowel, and it is lined by a simple columnar epithelium with microvillis, where the microvillis in the hindgut are sparsely populated. In contrast, the microvillis is significantly dense in population of the foregut and midgut with nearly even distribution. Goblet cells are distributed in the epithelial cells, but the number of which in the foregut and midgut is larger than that in the hindgut. In addition, the diameter of the intestine, the number and height of the intestinal villus are found to be decreasing from front to back. The digestive tract morphology of Opsariichthys bidens is in consistency with its predacity nature.