Microstructure and Ultrastructure of the Digestive System in Lamprey Lampetra japonica

The histological structure of digestive tract of Lampetra japonica was studied by light and electronic microscopy.Stratified cuboidal epithelium in the fold of oesophagus mucosa and transitional epithelium in the bottom of the fold were observed.Because of the life style specialization L.japonica lost its stomach.The fore-,mid-and hind-intestines were characterized by single-layered columnar epithelium,and there were numerous dense cilia and abundant cell organelles in the epithelial cells.The muscle bifers distributed obliquely.The lobules were not distinctly observed and there was no bile duct in the liver.The endocrine pancreas consisted of cell mass in different sizes and various shapes.The secretory epithelium of the buccal glands consisted of high columnar cells which contained numerous granules and tubular vesicles,some of which were zymogen-like.There were many tubular vesicular systems among these cells.In summary,there is a close correlation between the histology structure characteristic of digestive system and particular feeding behavior in this species.