半滑舌鳎(Cynoglossus semilaevis)消化道显微与超微结构

Structure and Ultrastructure of Alimentary Canal of Cynoglossus semilaevis

关键词:  半滑舌鳎  消化道  食道胃  黏液细胞  组织学

Key words:  Cynoglossus semilaevis  Alimentary canal  Oesogaster  Mucous cells  Histology

摘要:

采用解剖学、组织切片、电镜观察和2种染色技术研究了半滑舌鳎(Cynoglossus semilavis)消化道的组织结构特征。半滑舌鳎消化道可分为口咽腔、食道、食道胃、前肠、后肠5部分，观察了各部分消化道的显微和超微结构，测定了消化道各部分的黏膜褶皱数、黏膜褶皱高度、肌肉层(纵肌和环肌)厚度、黏液细胞相对密度等指标。结果显示，半滑舌鳎不具备结构特征明显的胃，摄食后，食道后部与肠道连接部形成一个囊状膨大结构，称之为食道胃；食道前部开始出现杯状黏液细胞，整个食道以Ⅲ型黏液细胞为主，食道胃中黏液细胞以Ⅲ型为主，前肠黏液细胞以Ⅳ型为主，后肠黏液细胞以Ⅱ型为主。研究结果为认识半滑舌鳎消化与吸收生理机制及研制人工养殖用饲料提供参考资料。

Abstract:

This study was designed to improve the understanding of the alimentary canal of Cynoglossus semilaevis. The alimentary canal of C. semilaevis can be divided into five sections, including oropharyngeal cavity, esophagus, esophagus and intestinal junction, foregut and hindgut. The structure and ultrastructure of alimentary canal of C. semilaevis were investigated using anatomical, histological and electronic microscopy methods. The number of mucosal folds, the height of mucosal folds, the thickness of muscle layers (longitudinal muscle and circular muscle), the density of mucus cells were measured and analyzed. The results showed that there was no obvious morphological stomach in C. semilaevis, evident by the lack of typical histological structure. However, a cystic structure, namly oesogaster, was formed in posterior part of esophagus following food intake, and oesogaster shrinked significantry during no food period. The principal structures of intestine canal include mucosal layer, submucosal layer, muscle layer and serosal layer. Oesogaster and intestine canal had little morphological difference based on electronic microscopic analysis. Each part of mucosal epithelial cell had mucus cells. Microvilli on the intestinal surface had no morphological difference. Microvilli of different sections, however, had differernces in length, with the longest on the foregut. The size and shape of mucus cells were also different. Top cytoplasm contained significant amount of mucous granules, while surface microvilli were relatively short, inward concaving and compact together. The goblet cells were found in the front segment of esophagus. In terms of mucous cell pattern, type Ⅲ mucous cell was the dominant cell type throughout the whole esophagus. Specifically, the mucous cells in oesogaster belonged to type Ⅲ, whereas foregut and hindgut segments mainly contained type Ⅳ and type Ⅱ mucous cells, respectively. The present study provides basic knowledge of digestive structure and mechanism of C. semilaevis and potentially can help to manufacture commercial diet for C. semilaevis.