Abstract:

The organizational structural characteristics of digestive system of fish are closely related to diet. To study the digestive physiological characteristics of reef fish Girella leonine, the organizational structural characteristics of digestive system were investigated by H.E staining. The correlation between the structural characteristics of tissue and the adaptability of diet and environment was discussed. The results are summarized as follows. 1) The esophagus tended to the cavity to form six thick folds, which had obvious striated muscle and mucous cells, and the folds had strongly expansion ability. Mucous cells were distributed between mucosa epithelium and were cone-shaped. 2) “V-shaped” stomach was divided into cardia, gastric body and pylorus. The transverse section of gastric gland was round and the lumen was surrounded by several gland cells. The muscular layer of the stomach was well developed, its inner was annulus structure and the outer was longitudinal structure. The stomach glands were mostly developed in the lamina of gastric body, the gastric mucosa formed many folds and the pyloric stomach had multi-level branch folds. 3) There are more than 150 branched diverticulum in the pyloric, and they can be divided into two branches. The cavity of the cecum was filled with mucosal folds. The epithelium of mucosa was composed of single columnar epithelial cells without goblet cells. 4) Liver was divided into two leaves, which showed a general structure of bony fish in histology. The liver cells were large and polygonal, with a size of nearly 30 μm. 5) The intestine had four convolutions, and the ratio of intestine length to body length was 1.52±0.06, the value was between herbivorous and carnivorous fish. There were lots of goblet cells distributing in the whole intestine. The intestine had well-developed villi of small intestine. The epithelium of the villus base caved into the lamina propria to form the intestinal gland. The gland opened to the adjacent villi base. As the main digestible site, the number and height of the villi were greater than those in the hindgut. In this study, we also discussed the relationship between the histology characteristic and the digestion and absorption of digestive system of Girella leonine. Results showed that the characteristics of digestive system of Girella leonina was typical of omnivorous fish digestive system.

Key words: Girella leonina, digestive system, algophagous, histology