放流前的大麻哈鱼消化系统发生发育的组织学研究

Ontogenetic development of digestive system in chum salmon Oncorhynchus keta before released

采用形态学观察与连续组织切片技术,对放流前的大麻哈鱼Oncorhynchus keta胚胎期(水温为8～10℃)和胚后期(水温为9～11℃)消化系统的发生发育进行观察和研究。结果表明:大麻哈鱼受精后第16天形成原始的消化管及致密的小肝细胞团;受精后第18天V型胃及口裂雏型形成,胰细胞出现;受精后第25天,肛门形成,消化道贯通;受精后第38天V型胃及胆囊发育形成;受精后第50天幽门盲囊出现;受精后第60天鱼体破膜,口能自由闭合,上、下颌及舌部出现早期齿,原始的胃腺细胞出现。破膜后第10天,消化道初步形成口咽腔、食道、V型胃、肠、肛门和幽门盲囊,仔鱼消化系统初步具备了摄食和消化外源性食物的能力;破膜后第70天,卵黄完全被吸收,各消化器官和结构逐步发育。此后随着鱼体的生长,消化器官逐步发育成熟,结构和功能逐渐完善。

The ontogenetic development of digestive system was histologically studied during embryonic period（at water temperature of 8-10 ℃） and post-embryonic period（water temperature 9-11 ℃） in chum salmon Oncorhynchus keta before released.The results showed that a simple digestive tract and compactive cell mass of small liver were formed 16 days after fertilization.The V-shaped stomach and gallbladder were observed by 38 days after fertilization,and pyloric caeca appeared by 50 days after fertilization.The embryo was hatched and the mouth was opened freely,the early teeth appeared on the tongue,upper jaw and lower jaw,and primitive gastric follicles cells were noted by 60 days after fertilization.The digestive tract was composed of buccal-oropharyngeum,esophagus,V-form stomach,intestine,anus and pyloric caecum.The digestive system of the alevins became capable of ingestion and digestion of extraneous foods 10 days after hatching.By 70 days after hatching,the yolk sac was completely exhausted,and the structure and function of the digestive organs were gradually developed.As the fish further grew,its digestive organ developed slowly,and functioned.