Histomorphological and histochemical researches on the digestive tract of the freshwater grass carp, Ctenopharyngodon idella (cypriniformes).

Ctenopharyngodon idella does not have a stomach, as is shown by the absence of gastric glands. The intestine is a simple coiled tube about twice the length of the body, having no valves and no ceca, and it is joined directly to the esophagus. The mucosa is fairly uniform in appearance, being thrown into folds which give it a mesh-like appearance. No multicellular glands can be detected in any part of the alimentary canal. Goblet cells are present: no differences are found in young specimens. Mucous in the goblet cells from young animals shows no differences in the various parts of the intestine. In the adult animals the mucous is markedly acidic in the first part of the intestine. In the young animals some migrant cells are present in the mucosa and in the connective tissue; these being more numerous in the fingerlings of 6--7 cm in length.