卵形鲳鳆消化系统的胚后发育

利用形态学和连续组织切片技术，研究了孵化后31d前的卵形鲳够（Trachinotusoyatus）仔、稚、幼鱼的消化系统发育，描述了其消化器官发育过程和组织学结构特征．研究表明，在水温为23—28℃的培育条件下，消化系统发育可划分为4个阶段，第1阶段（0—2d）：初孵仔鱼消化管仅为一细长的线状管，位于卵黄囊上方，不具备摄食和消化能力，为内源性营养阶段．第2阶段（3—5d）：口和肛门形成，消化道与外界相通，开始摄食．5d仔鱼卵黄囊完全吸收，出现肝脏、胰脏，为混合营养阶段，消化道分化成口咽腔、食道、胃、前肠和后肠．第3阶段（6—17d）：随着鱼体的生长，消化系统从结构和功能上逐步发育完善，进入到外源性营养阶段．仔鱼前肠中出现空泡，后肠中发现有嗜伊红颗粒，表明肠上皮细胞吸收了脂肪和蛋白质．17—18d仔鱼出现胃腺和幽门盲囊，标志着稚鱼期的开始．第4阶段（18—22d）：胃腺、幽门盲囊、肝胰脏等消化器官发育完成，鱼苗进入幼鱼期．结果表明，卵形鲳碜消化系统的发育是与仔、稚鱼的生长、形态发育和功能的完善相一致的．

Postembryonic development of digestive system of Trachinotus ovatus

The development of digestive system of larva,juvenile,and young Trachinotus ovatus from 0 to 31th days after hatching were studied with techniques of histology and morphology.Results showed that under the rearing condition of 23~28℃,the development of digestive system could be divided into 4 stages.Stage I was endogenous trophic stage at the age of 0 to 2 d.The digestive tract of newly hatched larva was a threadlike tube lying dorsal to the yolk-sac,with no feeding and digesting abilities.Stage Ⅱwas mixotrophic stage ranged from 3 to 5 d,the mouth and anus opened,the digestive tract ran through and the larvae began to feed.On the 5 d,the yolk was completely absorbed,the liver and pancreas appeared.The digestive tract was differentiated to buccopharyngeal cavity,esophagus,stomach,foregut and hindgut.Stage Ⅲ was exotrophic stage ranged from 6 to 17 d.The structure and function of digestive system developed gradually during this period.Vacuoles occurred in the foregut and there were esoinophilic granulae in hindgut,which indicated that lipid and protein were absorpted by epithelium cells of intestine.Gastric glands and pyloric caecum were observed in 17~18 d,indicating the beginning of juvenile period.Stage Ⅳ ranged from 18 to 22 d,when the digestive organs such as stomach gland,pyloric caeca,liver and pancrease developed completely,indicating the beginning of young fish period.In conclusion,development of the digestive system of T.ovatus were in accord with the growth,morphology development and perfection of functions of larva and junvenile.