Microscopic structures of digestive tract in pike eel {\sl Muraenesox cinereius}

By using light microscopes,it is detected that the digestive tract of the pike eel (Muraenesox cinereius) consists of distinguishable oesophagus,stomach and intestine.There are numerous large plicae in the oesophagus.Most area of the mucosa is covered by multi-layer squamous epithelium,while some local area is single-layered columnar epithelium.The epithelium,consisting of two types goblet cells,is characterized by the multitude of the goblet layers.In addition,it is found that there are some acidophilic cells distributed in the oesophagus epithelium near the basal cell.The muscularis externa of the oesophagus is thick.In the serosa,a large amount of fibers extend to the muscularis and connect with the submucosa.The Y-shaped stomach is divided into cardiac part,caecum gastricum and pyloric part.The caecum gastricum is well developed.In histology,the epithelium of stomach is constituted by single-layer columnar epithelium,under which,in the cardiac part and caecum gastricum,developed gastric glands present.The intestine is short.Its epithelium is composed of columnar cells with distinct microvilli.In the front part of intestine,the villi anastomose each other by their large number of branches.The capillary and smooth muscle fibers are abundant.The rectum mucosa epithelium is composed of single-layer columnar epithelium and pseudostratified ciliated columnar epithelium.Histological features of the digestive tract are consistent with the carnivorous habit of the pike eel.