ABSORPTION OF THE HORSE-RADISH PEROXIDASE IN THE SMALL INTESTINE OF CmCKEN

Holman J.: Absorption of the Horse-radish Peroxidase in the Small Intestine of Chicken. Acta vet. Brno, 47, 1978: 3-6. Localization of the horse-radish peroxidase was studied in the epithelium and stroma of the small intestitlal villi in the chic:, aged 37 days. The enzyme (molecular weight 40.000) was injected into the ligated jejunal loop. Its enteral absorption was shown to proceed via the senescent ent.ncytes. After the 3and 5-minute long exposure the enzyme occurred in the epithelial terminal web and in the cytoplasm of senescent enterocytes. After the 10and 20-minute long exposure the enzyme was shown in the vicinity of the basement membrane of the epithelium and near the blood vessels of the villous stroma. After the 30-minute exposure the horse-radish peroxidase was found in the intercellular spaces at the tips of the intestinal villi. Small intestine, senescent enterocyte, macromolecular transport. Horse-radish peroxidase is an important labelling material employed in research of transport of high-molecular substances. The enzyme can be visualized by both light and electron microscope and its amount can be quantitatively determined also in extremely small concentrations. Besides the well-known enzymatic digestion of food macromolecules, e. g. proteins, prior to their absorption by the small intestinal mucosa there is some evidence to indicate that through the adult intestinal wall small and nutritionally unimportant amounts of intact molecules can pass (Alexander et al. 1936; Danforth and Moore 1959). In other biochemical experiments free transfer of intravenously injected or endogenous proteins through the intestinal mucosa was observed (Wettefors et al. 1960; Campbell et al. 1961; Ghettie et al. 1967). All experiments studying the absorption of horse-radish peroxidase by the intestinal mucosa have been made on mammals (rats, mice) and evaluated by both the light and electron microscope. Hugon and Borgers (1968) and Hugon (1971) at i. v. or i. p. injection of peroxidase found the labelling substance to diffusely stain the cytoplasm of some absorptive cells. The other absorptive cells of the villous epithelium and of the crypts accumulated peroxidase in their apical parts. Cornell et al. (1971) found that after the intraluminal injection of peroxid]lse into the ligated jejunal or ileal segment of an adult rat the exogenous macromolecule can be transported into the intestinal absorptive cell by its typical vacuolar system and it can be transferred by these cells into the intercellular space of the lamina propria mucosae. The intestinal epithelial cells with diffusely staining cytoplasm are eonsidered to be senescent enterocytes. Ono (1975) electronmicroscopically localized the exogenous peroxidase after its intraluminal application in the small intestinal epithelium of rats during their postnatal development. The aim of the present work was to find the absorption sites of the exogenous protein (horse-radish peroxidase) in the jejunum of the chicken. Materials and Methods In the experiment White Leghorn chickens aged 37 days were employed. After a 24-hour long fast, through an incision the jejunal loop near the Meckel's diverticulum was exteriorized and ligated at two places. Under low pressure the horse-radish peroxidase (molecular weight 40.000)