Histological Study of the Digestive System Organogenesis for the Mandarin Fish, Siniperca chuatsi

The development of the digestive tract and accessory glands in the Mandarin fish (Siniperca chuatsi) larvae from hatching to 35 days after hatch (DAH) was morphologically and histologically examined using light microscopy. Hatched at the temperature varying from 18.0 to 20.0°C, the digestive tract of the newly hatched larva of the mandarin fish was a simple closed tube under the notochord and above the posterior segment of the oval yolk sac containing the oil globule. On 2 DAH, the mouth and the anus were opened, the digestive tract run through. On 4 DAH, the epithelium of the digestive tract was differentiated, the live and pancreas appeared, and fish began to turn endogenous feeding to exogenous feeding. On 5 DAH, the larvae begun to ingest exogenous food, the digestive tract was differentiated into five portions: buccopharyngeal cavity, esophagus, stomach, anterior and posterior intestine. The yolk was gradually absorbed and disappeared on 9 DAH. During the following developmental period of the larvae, the structure and function of the digestive system became mature gradually. Infranuclear vacuoles occurred in the anterior intestine on 7 DAH and esoinophilic granulae occurred in the posterior intestine on 8 DAH, which indicates the start of lipid and protein absorption. Gastric glands were observed on 13 DAH, which indicates the passage through the juvenile period.

Keywords
Siniperca chuatsi; Digestive system; Organogenesis; Histology; Morphology