工厂化养殖条件下豹纹鳃棘鲈消化系统组织学的观察

Histological observation on digestive system of Plectropomus leopardus under industrialized culture

采用解剖和组织切片技术,对工厂化养殖条件下全程投喂人工配合饲料的豹纹鳃棘鲈(Plectropomus leopardus)消化系统形态学和组织学进行研究。豹纹鳃棘鲈的消化道由食道、胃、幽门盲囊和肠道构成,消化道管壁由粘膜层、粘膜下层、肌层和浆膜层组成。食道短而粗,粘膜层向内腔突起形成纵行褶皱,上皮表层排列有杯状细胞。胃部膨大,为"Y"形,未见有杯状细胞,食道与胃的肌层均发达。幽门盲囊有3条,组织学结构与小肠相似。肠道在腹腔内呈"Z"形排列,比肠长为0.72±0.04,肠粘膜层向腔内突起形成发达的褶皱,多数形成二级褶皱,肠道各段均分布有杯状细胞。消化腺由肝胰脏和胆囊组成,肝脏分三叶,胰腺在肝脏内呈弥散性分布,胆囊呈长条状。本研究讨论了工厂化养殖条件下豹纹鳃棘鲈消化系统组织学特征与消化、吸收的关系,认为豹纹鳃棘鲈消化系统具备典型肉食性鱼类消化系统特征。

Plectropomus leopardus,east star spotted fish,is a kind of high-grade edible marine economic fish.Plectropomus leopardus has strong adaptability,and it is suitable for artificial breeding. In recent years,domestic and foreign scholars have done a lot of research on the biology and breeding of Plectropomus leopardus. Artificial breeding is developing rapidly in Hainan and a complete industrial chain of farming has formed,but histological study is almost blank. Histological study on digestive system of Plectropomus leopardus fed with artificial compound feeds under industralized culture is of great significance for factory farming.Experimental fish were fed with artificial compound feeds under industralized culture using flow-through mode. Five adults,with body length（ 28. 13 ± 1. 18） cm,weight（ 500. 10 ± 74. 16） g were randomly selected. After stopping feeding for 48 h the experimental fish were anesthetized and the abdominal cavity opened. The shape,position,colour of the entire digestive system were described and recorded. And the gastrointestinal tract and digestive glands were taken,intestinal length measured. From the front to the rear section were esophagus,stomach,pylorus,intestine,liver and pancreas. Tissue blocks were cut,and fixed with 4% paraformaldehyde,conventionally dehydrated,paraffin-embedded,sliced to 5 μm pieces,HE stained,mounted with neutral gum. Furthermore,the liver was frozen sliced,oil red O stained and fat cells were observed.The digestive tract of Plectropomus leopardus was made up of oesophagus,stomach,pyloric caeca and intestine,while the wall of digestive tract included mucous,submucosa lamina,lamina muscularis and adventitia. The Y- shaped stomach was inflated,where no goblet cells were found,and esophagus and stomach both had well-developed muscularis. Between the stomach and foregut was pyloric,whose histological structure was similar to that of intestinal tract. The intestinal tract was like ＂Z＂in the abdominal cavity,andintestinal length ratio was 0. 72 ± 0. 04. Intestinal mucosal layer protuberated into the cavity,forming developed folds,the goblet cells were distributed in each section of intestinal tract. The digestive glands consisted of hepato-pancreas and cholecyst. The liver was separated into three leaves,the pancreas were dispersedly distributed; the gallbladder had a long strip shape. Esophageal mucosal folds were the highest in the digestive system,reaching（ 1 859. 36 ± 669. 05） μm,and there was a significant difference with stomach.The submucosa of the stomach was the thickest,up to（ 603. 78 ± 122. 77） μm. The circular muscle of the esophagus and stomach was very thick,up to（ 1 068. 66 ± 116. 70） μm and（ 1 072. 33 ± 332. 60） μm. The longitudinal muscle of stomach was the thickest,up to（ 432. 40 ± 115. 22） μm. The serosa of stomach was the thickest,up to（ 53. 18 ± 55. 92） μm. Stomach did not contain goblet cells,the goblet cell density of hindgut was the maximum,up to（ 35. 56 ± 8. 09） μm. However the goblet cells of the esophagus were the largest,the diameter up to（ 29. 23 ± 6. 60） μm,short diameter up to（ 19. 06 ± 4. 21） μm. The long diameter of hepatocytes was（ 14. 71 ± 2. 51） μm,the short diameter was（ 9. 89 ± 1. 95） μm,irregular oval,the cell nucleus were large and round,diameter was（ 3. 35 ± 0. 26） μm. Oil red staining showed that cytoplasmic contained a lot of fat,most in liver cells,and cell nucleus were vacuolated lipid drops to one side.This study discussed the relationship between histological characteristics of digestive system of Plectropomus leopardus and the digestion and absorption under industrialized culture and considered that the histology of digestive system of Plectropomus leopardus had typical characteristics of digestive system of carnivorous fish.