斜带石斑鱼消化系统胚后发育的组织学研究

利用形态学和连续组织切片技术，对出膜后1-60d的斜带石斑鱼各期仔鱼、稚鱼和幼鱼的消化系统进行了光镜观察，描述了其消化器官发育过程和组织学特性。研究表明，实验水温为22.0-27.8℃时，孵化后第4天，上下颌形成，卵黄囊被吸收，消化系统明显分化成食道、胃、肠、直肠以及肝脏、胆囊和胰脏等，鱼体由内源性营养转向外源性摄食营养，表明其消化系统的形态变化与食性的变化相适应。此后随着鱼体的生长，其消化系统从功能和结构上逐步完善成熟。胰脏在出膜后第4天出现，是和肝脏相互分开的一个独立的器官，但是发育到第35-60天，位于肠道后部的胰脏组织内出现许多大空泡。

Histological studies on post-embryonic development of the digestive system of Epinephelus coioides

The development of the digest ive system and its associated glands was examined histologically in Epinephelus coioides from the f irst day ( f irst day pos-t hatch) until 60th day after hatching. Specimens for this study were hatched f rom naturally spawned into artificially broodstock and maintained indoor cement tanks( 22. 0 - 27. 8 e ) . During the f irst 4 days after hatching, the formation of the oral jaw apparatus, lengthening of the digestive tube, the resorption of yolk sac, the digestive glands ( liver, gal-l bladder and pancreas) appearance, and muco sae differentiation are the most conspicuous elements of development . The larval digestive system is morphologically ready to process external food at the time of mouth opening ( 4 days after hatching) . The most noticeable events occurring during the following period of independent life are an increase in mucosal folding, cellular differentiation in the luminal epithelia, gut segmentation, liver growth and pancreas development. The digestive tract consists of clearly distinguishable oesophagus, stomach, intest ine and rectum. The major digestive glands include liver, gal-l bladder and pancreas. Then, these digest ive tract and digest ive glands become mature gradually, and complete the morphological digestive features characteristic of the juvenile stage with increasing age and feeding activity. The pancreas is composed of small independent masses in 4 days in larvae, and spread along the upper intestine with the larvae growth, but in the adult, it is difficult to discern. Although the entire larval period, from hatching to metamorphosis ( from larvae and juvenile stage to fry ) , was under consideration, the observations were concentrated on the most dynamic early stages of development occurring after hatching. It is expected that this information will improve our understanding of larval or juvenile digestion physiology and will be useful in design of opt imal rearing techniques and in the development of art ificial food for the larvae.