Structural classifications in the digestive tract of short mackerel, Rastrelliger brachysoma (Bleeker, 1865) from Upper Gulf of Thailand

Abstract

This study was the first attempt on the classification of the gross anatomy with histological structures of the digestive tract in the Rastrelliger brachysoma. Based on gross anatomical analysis, the digestive tract (65.68±7.06 cm, n = 25) is distinctly composed of four parts; oesophagus, stomach, pyloric caeca and intestine, respectively. Base on the histological analysis of the digestive tract, it is composed of four layers: mucosa, submucosa, muscularis and serosa. The epithelial lining of anterior oesophagus was shown to be a simple squamous epithelium whereas posterior oesophagus, stomach and intestine were simple columnar epithelium. The surface of this epithelium positively stained with both Periodic Acid Schiff (PAS) and alcian blue (AB). The posterior oesophagus exclusively showed high longitudinal fold with numerous gastric glands in the mucosal layer, which is similar to the stomach structure (cariac and pylorus). Numerous pyloric caeca about 220-225 pieces, were detected between the stomach and intestine regions. Finally, the intestinal coefficient (IC) was 3.69±0.47 cm. The anterior intestine presented either various longitudinal folds or various goblet cells. The short longitudinal folds of posterior intestine were in the higher number of goblet cell than the previous part.

Keywords

• histology
• histochemistry
• digestive tract
• Rastrelliger brachysoma
• Thailand