牙鲆(Paralichthys olivaceus)消化道形态学及组织学研究

Study of the Morphology and Histology of the Digestive Tract of the Bastard Halibut Paralichthys olivaceus (Temminck &Schlegel)

采用大体解剖及光镜技术研究了牙鲆消化道形态学和组织学。牙鲆消化道由口咽腔、食道、胃、小肠、幽门垂和直肠构成。牙鲆口咽腔较大 ,牙锥形 ,为颌齿 ,舌三角形 ,粘膜表面为复层扁平上皮 ;食道粘膜也衬着复层扁平上皮 ,在食道起始处存在少量味蕾和较多的杯状细胞。由食道到胃 ,杯状细胞逐渐减少直至消失。肌肉也由横纹肌变成平滑肌。胃稍膨大 ,弯曲呈 J型 ,粘膜上皮为单层柱状上皮。贲门部、胃体和幽门部均有胃腺分布 ,尤以胃体处最多。小肠短 ,为体长的 1/ 2左右。小肠上皮为具微绒毛的单层柱状上皮 ,幽门垂 4个 ,无括约肌 ,组织结构与小肠相似。直肠粘膜上皮为假复层柱状上皮 ,粘膜上皮中散布着较多的杯状细胞 ,环肌比较发达。牙鲆的消化道组织特点表明 ,其消化过程的特性就是食物停留胃内的时间较短 ,因而牙鲆的进食间隙也较短。

The anatomy and histology of the alimentary tract in larval Bastard halibut were studied using light microscopes. The digestive tract consists of the buccal-pharynx cavity, oesophagus, stomach, intestine, pyloric caeca and rectum. On the big buccal-pharynx cavity there is a triangular tongue and many keen mandibular teeth. The mucosa layer of buccal-pharynx cavity is stratified squamous epitheli, so is the oesophagus mucosa layer. On the beginning of oesophagus there are a few taste buds and many goblet cells. At the transition from the oesophagus to the stomach, the stratified epithelium with goblet cells changes abruptly to the columnar epithelium with no goblet cells, meanwhile the skeletal muscle changes to smooth muscle; The J-shaped stomach has single-layered columnar epithelium, the gastric glands distribute on all parts of the stomach, especially on the body division; The intestine has many mucosal folding, and its epithelium is composed of columnar cells with a distinct microvillus brush border. The histological structure of the pyloric caeca is the same as the intestine. The rectum mucosa epithelium is pseudostratified columnar epithelium and has many goblet cells. From the characteristic of the digestive tract it is known that the time which food stay in the stomach is very short, so it is needed to feed this fish every several hours in aquaculture practice.