The Cytological Effects of Infusion of Luminal Polyethylene Glycol on the Rat Small Intestinal Mucosa

Abstract

Summary.An isolated sac of rat upper small intestine was prepared. Its lower end was drained to the skin.Solutions of known volume and composition were infused into the sac and the intestinal mucosa was examined by light and electron microscopy. Infusion of isosmotic (16.8% w/v) polyethylene glycol (PEG) resulted in prompt and progressively severe damage to enterocytes at the top of the villus, while goblet cells and basal-granulated cells were apparently unaffected. Thus, after 6-72hrs a cap of goblet cells and basal-granulated cells accumulated at the tip of the villus, while the enterocytes underwent vacuolation and disintegration.Infusion of an isosmotic mixture of 1% PEG and 5.1% glucose caused no damage near the site of infusion, but damaged the intestinal sac further distally.The infusion of distilled water also damaged enterocytes, but the pattern of damage was different from that seen with PEG. Infusion of isosmotic glucose solution appeared to cause no damage to the mucosa. The damage caused by PEG infusion had disappeared 6hrs after the replacement of PEG by an infusion of isosmotic glucose solution.These results were discussed in reference to the turnover and kinetics of the intestinal epithelium.

‘Luminal Nutrition’ versus ‘Functional Work-Load’ as Controllers of Mucosal Morphology and Epithelial Replacement in the Rat Small Intestine

“…In the comparison of galactose-or glucose-infused with unin fused sacs, the difference in slope was not significant (0.10 > p > 0.05). Histo logical examination showed no evidence of mucosal damage like that described by Clarke and Kobayashi (8) in any specimen.…”

Source of net water and electrolyte loss following intestinal ischaemia

“…In view of the complication imposed by the vascular stasis referred to above, we have also attempted to induce similar morphological and functional changes in the epithelial layer by chemical means to obtain further information on the source of secretion following disruption of the villus epithelium. Although the local application of corrosive substances, such as acids [11,17,28], formalin [35], or concentrated solutions of polymers [4], has been used previously to explore the regenerative potential of the intestinal mucosa, only three attempts seem to have been made to destroy selectively one part of the intestinal mucosa by chemical means: Roggin et al [33] and Browning et al [1] damaged the tips of the villi by the introduction into the ileum of very hypertonic solutions of sodium sulphate, to which the crypts were apparently refractory, and Kingham et al [20] used unionised acetyl-salicylate to obtain analogous effects. In the present study, we have ostensibly achieved the same results by exposure of the dog ileal mucosa in vivo to a solution of Triton X-100.…”

<b>IMMUNOCYTOCHEMISTRY AND ULTRASTRUCTURE OF SEGI’S </b><b>CAP </b>

“…The specificity of the immunocytological reaction was checked by the following controls: ( 1) the omission of the first layer; (2) incubating the tissue sections with normal rabbit or guinea pig sera in place of the primary antisera;…”

“…The ultrastructural features of the basalgranulated cells in Segi's cap which are not known in the corresponding cells dispersed in the adult intestinal mucosa are as follows: (1) Basal-granulated cells in Segi's cap frequently contained two populations of cytoplasmic granules: one resembled the secretory granules of the adult type basal-granulated cells, and the other was represented by much larger granules measuring up to 1 rim in diameter. The latter resembled the so-called "precursor" type secretory granules described by Moxey and Trier ( 10) in the "precursor" and "transitional" cells in the human fetal small intestine.…”