Scanning electron microscopy of isolated epithelium of the murine gastrointestinal tract: Morphology of the basal surface and evidence for paracrinelike cells

Abstract

By using the method of Bjerknes and Cheng, isolated murine gastrointestinal epithelial sheets were prepared for scanning electron microscopy. Examination of isolated epithelium from fundic stomach revealed numerous branched gastric glands. Parietal cells were easily detected bulging from the basal surface of the glandular epithelium. The basal surface membrane of parietal cells appeared smooth, with only sparse microvilluslike projections, whereas adjacent glandular cells had numerous 1- to 2-micron fingerlike projections which interdigitated laterally with similar processes from adjacent cells. Occasionally, paracrinelike cells having long cytoplasmic processes ranging from 10 to 20 micron in length were observed on the basal epithelial surface of the stomach and the colon, but not the small intestine. In isolated intestinal epithelia, the basal surface of crypt epithelial cells showed extensive cytoplasmic interdigitations, but no distinct morphology permitting recognition of individual cell types. Various stages of intestinal crypt bifurcation were seen. Craterlike spaces in the basal surface of crypt epithelium, presumably due to migrating leukocytes, were also numerous. Examination of the luminal surface of the isolated intestinal epithelium revealed that intimate associations between epithelium and mucosal-associated microorganisms were maintained, thus suggesting that minimal alterations in surface morphology were incurred by epithelial isolation. These observations on epithelial structure suggest that isolated gastrointestinal epithelia may be well suited for physiological studies of epithelial function and interactions with the microbial flora.

Resolving the Contradictory Functions of Lysine Decarboxylase and Butyrate in Periodontal and Intestinal Diseases

“…They shed from the flat surface of the colon, and complete turnover occurs every 5–7 days. Reprinted with permission from [ 24 ]. Copyright 1986 John Wiley & Sons, Inc.…”

An enteroendocrine cell‐based model for a quiescent intestinal stem cell niche

“…Various studies have described highly polarized somatostatin‐containing enteroendocrine cells with basal axon‐like processes that contain secretory granules and extend along the basement membrane and beneath neighbouring cells (Larsson et al . 1979; Tsubouchi & Leblond 1979; Magney et al . 1986; Satoh et al .…”

Understanding epithelial homeostasis in the intestine

“…Up to 10 crypts merge into fingerlike villi. This can be seen very nicely by scanning electron microscopy 9 on sheets of intact epithelium isolated by EDTA perfusion (see Fig. 4 in 10).…”

“…The Dlb-1 locus generates an intestinal binding site for the Dolichos biflorus agglutinin (DBA) lectin and the mutagen, N-nitroso-N-ethylurea (NEU) induces random genetically marked clones of DBA-positive cells in epithelia of Dlb-1 −/− SWR mice whose cells are otherwise unlabeled by DBA 62 . They applied this to the SI epithelium using isolated intact crypt/villus preparations, 9 which had two crucial advantages: they provided a large sample of crypts (thousands) so that statistical analysis became possible, even of rare incidences, and they offered superior cytological detail and accurate cell positional information by Nomarski microscopy 10 . Starting three days after NEU treatment and at intervals up to 154 d, they analyzed in crypts labeled with peroxidase-labeled DBA the position, composition with respect to cell types and longevity of the observed DBA+ cell clones.…”