银鲳消化道形态与组织学结构特征及其消化酶活性

为了解银鲳(Pampus argenteus)消化道结构特点与其功能及食性的相关性, 采用解剖、石蜡切片、AB-PAS染色及酶活性检测技术对银鲳消化道的形态、组织结构、黏液细胞分布及消化酶活性进行研究。结果显示, 银鲳的消化道由口咽腔(舌)、食道侧囊、食道、胃及肠构成, 胃肠交界处有很多幽门盲囊。食道侧囊呈椭球形, 食道粗短, 胃呈U型, 肠有多个盘曲, 肠指数为2.03。舌上皮内有少量味蕾及较多黏液细胞。食道侧囊、食道、胃及肠均由黏膜层、黏膜下层、肌层及浆膜组成。食道侧囊内皱襞较发达, 被覆复层扁平上皮, 内含较多黏液细胞, 且以Ⅳ型为主, 皱襞顶端及侧面有内含角质刺的次级突起; 黏膜下层及肌层中有固定皱襞的骨质脚根; 侧囊内胃蛋白酶活性较高。食道内皱襞较高, 被覆复层扁平上皮, 内含较多黏液细胞, 且以Ⅳ型为主。胃内皱襞发达, 被覆单层柱状上皮, 未见黏液细胞分布; 胃腺发达, 胃内蛋白酶活性较高。肠道内褶襞多, 高度呈先下降后上升趋势, 黏液细胞密度前、中肠较高, 后肠较低, 且均以Ⅰ型为主; 肠道内胰蛋白酶、脂肪酶、淀粉酶及碱性磷酸酶活性较高。幽门盲囊组织结构与肠相似。银鲳的消化道结构特点、黏液细胞分布及消化酶活性与其功能及偏肉食的杂食性相适应。

MORPHOLOGY,HISTOLOGICAL STRUCTURE CHARACTERISTICS AND DIGESTIVE ENZYME ACTIVITIES OF THE DIGESTIVE TRACT OF PAMPUS ARGENTEUS

To study the relationship between feeding habits and structural characteristics and functions of the digestive tract of Pampus argenteus, we used morphological, histological, histochemical (AB-PAS) and enzymological techniques to investigate the morphological and histological structures, mucous cell distributions and digestive enzyme activities of the digestive tract of P. argenteus. Our results showed that the digestive tract of P. argenteus consist of six parts: an oropharyngeal cavity with a short tongue, an ellipsoidal esophageal sac, a stubby esophagus, a U-shaped stomach, a multiple coils intestine with index 2.03 and a large number of pyloric sacs. In the oropharyngeal cavity, several taste buds and three types of mucus cells were detected in the stratified squamous epithelium of tongue. The esophagus sac, esophagus, stomach, pyloric sac and intestine are all composed of mucosal layer, submucosa, muscle layer and serous membrane. The esophageal sac contains primary and secondary protrusions, which were covered with stratified squamous epithelium, a special structure (horny spur) and a large numbers of type Ⅳ mucus cells were observed in the epithelium, and the esophageal sac showed a high level of pepsin activity. The esophagus showed high mucosal folds with a stratified squamous epithelium, a large number of mucus cells were detected in the epithelium, which are dominated by type Ⅳ. The stomach was abundant in gastric glands, no mucus cell was observed in it. A high level of pepsin activity was detected in the stomach. The intestine shows a single columnar epithelium, four types of mucus cells were observed in the epithelium, which are dominated by type Ⅰ. The total density of mucus cells increased from anterior intestine to middle intestine, but decreased from middle intestine to posterior intestine. while the height of mucosal fold was first decreased and then increased from anterior intestine to posterior intestine. The intestine also showed high level of trypsin, lipase, amylase and alkaline phosphatase activities. The structure of pyloric sac was similar to intestine, it enhances the digestive and absorptive functions of intestine. In conclusion, the morphological and histological characteristics, mucous cell distributions and digestive enzyme activities in the digestive tract of P. argenteus adapted to its omnivorous feeding habits.