PRELIMINARY STUDY ON ENDOCRINE CELLS IN THE GUT OF THREE CYPRINID FISHES

By using the Grimelius argyrophil staining method, an investigation was made into the endocrine cells in the gut of three cyprinids with different feeding habits, grass carp(Ctenopharyngodon idellus), common carp(Cyprinus carpio)and whitefish(Erythroculter ilishaeformis). Endocrine cells are detected throughout the gut of all three species. The number of endocrine cells is most in the anterior segment of the foregut, and decreases towards the posterior end. Endocrine cells are seldom found in the rectum of C. carpio and E. ilishaeformis. But in C. idellus, the number of endocrine cells is slightly larger in the rectum than in the anterior segment of the hindgut. Endocrine cells are distributed in every part of the gut folds and are most abundant at the base of the folds. Most endocrine cells seem to be of the open type. They lie between the intestinal epithelial cells and goblet cells, and their cytoplasmic processes extend to the lumen of gut. Only a small number of endocrine cells have the feature of both open and close types; the basilar cytoplasmic process extends to the adjacent cells or intercellular space while the apical cytoplasmic process extends to the lumen of gut. In the intestinal epithelium, there is a group of round granules that show similar argyrophil staining characteristics as the enteroendocrine cells.