Étude cytophysiologique de l'épithélium intestinal du poisson-chat (Ameiurus nebulosus L.)

The ultrastructure of the intestinal epithelium was studied in the catfish (Ameiurus nebulosus L.) and four morphofunctional sections were recognized. The proximal segment that adjoins the stomach is involved in the absorption of alimentary lipids; these nutrients are present in absorptive cells as two different kinds of fat globules: a particulate form, which is the "exportation" form, and a reserve form. The enterocytes of the middle segment possess the ultrastructural differentiations typical of cells involved in the absorpiton of macromolecules: numerous pinocytotic figures, a tubulovesicular network, and absorptive vacuoles. The introduction into the intestinal lumen of exogenic macromolecules (horseradish peroxidase, ferritin, glycogen) indicated that these cells are capable of ingesting protein and polysaccharid macromolecules. The two terminal intestinal segments (distal and preanal) do not seem very much involved in the absorption of food. The epithelium of the preanal segment contains only one type of cell which is involved in the synthesis of mucopolysaccharid-like material.[Journal translation]