Study on histology and histochemistry of digestive tract in Sebastiscus marmoratus

In the paper,the histology and histochemistry of the digestive tract in Sebastiscus marmoratus were studied by optical microscopes.The digestive tract in Sebastiscus marmoratus consists of the buccal-pharynx cavity,oesophagus,stomach and intestine.The buccal-pharynx cavity was large and there were serration cingula on the upper jaw and mandible,vomer and palatine bone;The mucosa was composed of stratified squamous epithelium with many mucous secretory cells and a few goblet cells in buccal-pharynx cavity;There were two regions in the oesophagus,including cranial with pavement epitheliums and caudal with simple columnar epitheliums,in which there were many goblet cells and mucous secretory cells as well as unusual glands in the lamina propria;The Y-shaped stomach was divided into three portions and had a single-layered columnar epithelium under which well-developed gastric glands and gastric pits were present.Sphincter was obvious in the pyloric stomach,and gastric pits had not been detected in the epithelium;There were 8-9 pyloric caeca at the joint of the stomach and intestine,of which the morphologic and histological characters were similar to the cranial intestine's.The intestine epithelium was composed of simple columnar cells with a distinct brush border,in which there were many goblet cells.Meanwhile the average intestinal coefficient of Sebastiscus marmoratus was calculated,which came to about 0.54.The location and semi-quantification of alkaline phosphatase,acid phosphatase,carboxylic esterase and mucosubstances in the digestive tract of Sebastiscus marmoratus were studied by histochemistry.The results indicated that the absorption role was supported by the presence of an intense alkaline phosphatase activity in the epithelium of the pyloric stomach,pyloric caeca and intestine;The presence of abundant acid phosphatase in the apical border of the stepithelium of the pyloric caeca and the intestine showed that these cells were actively involved in the absorption and intracellular digestion of nutrient substances;And also,esterase activity were detected in the lamina propria of cardiac and fundic stomach,and apical border of the epithelium of the pyloric stomach had the intense activity.There were many mucous cells in the whole digestive tract which played an important role in the lubrication and absorption of nutrients;Large quantities of acidic mucous cells were detected in the oesophagus epithelium,and the stomach epithelium had many neutral mucous cells,while in the intestine,the distribution of neutral mucous cells was reducing from the cranial intestine to the caudal intestine,but the distribution of acidic mucous cell was reversed.The results proved that the histological and histochemical features of its digestive tract were consistent with the carnivorous habits of Sebastiscus marmoratus.