Showing papers on "Crypt published in 1984"

Partitioning of paracellular conductance along the ileal crypt-villus axis: a hypothesis based on structural analysis with detailed consideration of tight junction structure-function relationships.

Abstract: Current models of intestinal transport suggest cells which absorb ions are located on the villus while secretory cells are located in the crypt and putatively have paracellular pathways which are highly conductive to Na+ One approach to assess possible variation in small intestinal paracellular conductance along the crypt-villus axis is to morphometrically analyze the structural aspects of crypt and villus tight junctions (TJs) which relate to paracellular resistance Such detailed analysis of junctional structure in this heterogeneous epithelium would permit one to compare intestinal TJ structure-function relationships with those in a structurally simpler epithelium such as that of toad urinary bladder This comparison would also be of considerable interest since previous similar comparisons have failed to consider in detail the geometric dissimilarity between these two epithelia We applied light, electron microscopic, and freezefracture morphometric techniques to guinea pig ileal mucosa to quantitatively assess, for both crypts and villi, linear TJ density, relative surface contributions, and TJ strand counts Mean linear TJ densities were 768 m/cm2 for crypt cells and 218 m/cm2 for villus absorptive cells Mean TJ strand counts were 445 for undifferentiated crypt cell TJs and 603 for villus absorptive cell TJs The villus constituted 87% and the crypt 13% of total surface We utilized these data to predict paracellular conductance of cryptsvs villi based on equations derived from those of Claude (P Claude,J Membrane Biol 39:219–232, 1978) Such analysis predicts that 73% of ileal paracellular conductance is attributable to the crypt Furthermore, we obtained literature values for paracellular resistance in mammalian ileum and toad urinary bladder and for toad bladder TJ structure and linear density and constructed a relationship which would allow us to more accurately compare TJ structure-function correlates between these two epithelia Such a comparison, which considers both surface amplification and TJ structure and distribution in these epithelia, shows that one would predictin vitro measured values for paracellular resistance should be approximately two orders of magnitude less in mammalian ileum than in toad urinary bladder This predicted discrepancy (115-fold) correlates well with the observed difference (100-fold) These findings suggest that highly similar TJ structure-function relationships apply to these geometrically dissimilar tissues and that, in mammalian ileum, the crypt compartment may be responsible for the majority of net ileal paracellular conductance We speculate that high crypt linear TJ density and low crypt TJ strand counts may serve as the structural basis of massive paracellular Na+ movement which is coupled to active Cl− secretion and appears to originate from the crypt following exposure to intestinal secretagogues

The effects of starvation and refeeding on intestinal cell proliferation in the mouse

Abstract: The effects of starvation and refeeding on intestinal cell proliferation were studied in four sites of the mouse intestine. Control mice were studied at different times of day in order to compensate for any circadian variations in proliferation. A circadian rhythm in crypt cell production rate was observed in all the sites of the small intestine and colon, and this rhythm appeared to be entrained to the food intake. The fractional crypt cell production rate decreased in all sites of the intestine after 24 h starvation, and remained low until 9 h after refeeding, when there was a marked increase in the crypt cell production rate of all the small intestinal sites, especially the proximal sites. There was little change in colonic crypt cell production rate until 12 h after refeeding, when there was a large increase in cell production. The crypt cell production rate of all sites then returned to control values for the remainder of the investigation. Crypt cell number decreased after refeeding and villus cell number increased, however a similar effect was observed in the control animals, nevertheless the changes in villus cell population of the refed mice occurred before any increase in crypt cell production, suggesting that cell migration from crypt to villi is not immediately dependent on cell proliferation.

Immunohistochemical and biochemical demonstration of the change in glycolipid composition of the intestinal epithelial cell surface in mice in relation to epithelial cell differentiation and bacterial association.

Abstract: We have previously demonstrated the appearance of fucosyl asialo-GM1 (FGA1) in the small-intestinal epithelial cells of germ-free mice via the induction of GDP-fucose: asialo-GM1 (GA1) alpha(1 leads to 2) fucosyltransferase (FT) after the conventionalization of these animals (Umesaki Y, Sakata T, Yajima T: Biochem Biophys Res Commun 105:439, 1982). The present study, based on this earlier work, demonstrates the changes in the glycolipid antigens of the small-intestinal epithelial-cell membrane as shown immunohistochemically with specific antibodies raised against asialo GM1 (GA1) and FGA1. In germ-free mice, GA1 was localized both in the villus cells and in the crypt cells. In the process of conventionalization, FGA1 appeared in the villus cells while the GA1 content of these cells was decreased. Four to 5 days after the conventionalization procedure, the fluorescence produced by anti-FGA1 was strongest in the villus cells, while that produced by anti-GA1 was detected only in the crypt cells. At this same time the FT activity of the small-intestinal mucosa was highest, with most of the GA1 apparently being converted into FGA1, as shown in the paper cited above. Thereafter, the GA1 content of both the villus and crypt cells again increased greatly. On the other hand, the fluorescence produced with anti-FGA1 decreased, and could no longer be detected 14 days after conventionalization. The activity of FT, measured biochemically in epithelial cells differentially isolated from the villus tip to the crypt, was greater in the villus than in the crypt region. This confirmed the intense staining with anti-FGA1 that was seen in villus cells. The fluorescence produced by the two anti-glycolipid antibodies used in the study distributed not only in the microvillus membrane but also to some extent in the basolateral membrane. The localization of the respective glycolipids contrasted with that of the glycoprotein sucrase--isomaltase enzyme complex, the fluorescence of which was exclusively confined to the microvillus-membrane side of the villus cells.

Stimulation of Rat Colonic Crypt Cell Proliferative Activity by Wheat Bran Consumption during the Stage of 1,2-Dimethylhydrazine Administration

Abstract: The effect on colonic epithelial cytokinetics of feeding a 20% wheat bran dietary supplement, either during and/or after the stage of carcinogen administration with 1,2-dimethylhydrazine, was examined in 48 male Sprague-Dawley rats fed defined diets for up to 31 weeks. Nutrient intake and body weight gain were equivalent in all groups of animals. All subgroups of rats fed bran, either during and/or after carcinogen administration, developed colonic crypt cell hyperplasia (p less than 0.05), this being greater in the proximal than in the distal colon. Autoradiographic studies showed a significant increase in proximal colonic crypt cell-labeling index, proliferation zone size, and migration distance in those rats fed wheat bran during the period of carcinogen administration (p less than 0.05). The increase in epithelial cell proliferation activity was most marked in the upper two-thirds of the crypt. These data show that there is a greater stimulation of crypt cell proliferation activity when wheat bran is consumed during the stage of carcinogen administration as compared to the stage following carcinogen exposure. This alteration in mucosal cytokinetics appears to be the mechanism by which wheat bran consumption enhances rat colon carcinogenesis during the period of dimethylhydrazine treatment.

Late effects of irradiation in mouse jejunum.

Abstract: SummaryThe response of mouse jejunum at intervals up to 1 year after single ‘priming’ doses of X-rays has been assessed by crypt survival after retreatment with single doses of X-rays and morphometric analysis of changes in the intestinal submucosa. The first ‘priming’ dose was given as a single dose to the whole abdomen. To assess crypt survival, groups of mice were retreated to the whole body with a range of test doses 2, 6 or 12 months later, while other groups of mice were given only the priming doses. These data were compared to crypt survival in mice not previously irradiated.The crypt dose-survival curves in mice re-irradiated at all three intervals after priming irradiation were displaced to higher doses in pre-treated than in non-pre-treated mice and were characterized by higher D0 values. Misonidazole given before the test exposure reversed this effect so that the dose survival curve for crypts in pre-treated mice were superimposed on that for mice not previously irradiated, suggesting that the ...

Tonsillar changes in pigs given pseudorabies (Aujeszky's disease) virus.

Abstract: All of the eight 5-day-old pigs orally given pseudorabies (Aujeszky's disease) virus developed tonsillitis. The initial changes occurred in the subepithelial area between the lymphoid nodule and the crypt epithelium, showing a characteristic pattern of necrosis. The necrosis became more severe and gained access into the lymphoid nodule and crypt epithelium. Coincident with the histopathologic changes, numerous specific immunofluorescences were detected, first in the nucleus and in some parts of the cytoplasm of cells distributed in the subepithelial area. The fluorescence subsequently spread into adjacent lymphoid nodules and crypt epithelial cells. Ultrastructurally, many enveloped virus particles were detected in the center of the necrosis. Thereafter, the crypt epithelial cells also underwent degeneration, and a small number of virus particles were detected in the nucleus of the degenerating epithelial cells. In the more advanced stage, the enveloped virus particles were discharged into the crypt lumen.

Death of intestinal crypts and of their constituent cells after treatment by chemotherapeutic drugs.

Abstract: The number and spatial distribution of necrotic cells in the jejunal crypts of mice, has been measured after treatment by each of 6 cytotoxic drugs. At the LD10/8 day dose of each drug, the majority of necrotic cells were found below position 9 and numbers per crypt were similar for all drugs (approximately 8). These findings resemble those for radiation. However, major differences between agents were found in the calculated numbers of the microcolony-forming units (MFU) that determine overall crypt survival or ablation after high doses of cytotoxic agent. Numbers of MFU as assayed by radiation were approximately 80 per crypt, but only 2 when assayed by mechlorethamine hydrochloride, adriamycin and 5-fluorouracil, and 7 using BCNU. No crypts were destroyed by either cyclophosphamide or actinomycin D, despite the appearance of numerous necrotic cells in the lower part of the crypt. We conclude that in drug-treated intestine, necrotic cells may arise from a non-MFU compartment and the incidence and distributions of such cells are likely to be poor indicators of the response of the MFU.

Cell proliferation in gastrointestinal carcinogenesis.

Abstract: During the course of carcinogenesis in the intestinal tract a series of proliferative changes occur which may represent pre-neoplastic abnormalities. These include progressive crypt hyperplasia, expansion of the proliferation zone within the crypt and alterations in the numbers and distribution of proliferating cells. The literature documenting these changes has been reviewed and their significance as pre-neoplastic phenomena assessed. Major problems include the differentiation of coincidental adaptive changes from truly pre-neoplastic ones, and the integration of morphological and kinetic observations.

Mechanism of the regulation of the 1α,25-dihydroxyvitamin D3 receptor in the rat jejunum by glucocorticoids

Abstract: The distribution of 1 alpha,25-dihydroxyvitamin D3 (1,25-(OH)2D3) receptors in isolated jejunal villous and crypt cells was investigated in normal and adrenalectomized male rats, and also in animals treated with the synthetic glucocorticoid, dexamethasone, and/or the glucocorticoid antagonist, 11-deoxy-cortisol. Adrenalectomy caused an increase in 1,25-(OH)2D3 receptors whilst dexamethasone treatment led to a reduction in receptor number. 11-Deoxy-cortisol was able to reverse the 'down-regulation' effect caused by glucocorticoids. In all cases, the changes in receptor numbers were more pronounced in crypt cells. The data suggest that, in the small intestine, glucocorticoids may control the synthesis of 1,25-(OH)2D3 receptors via the mediation of a glucocorticoid receptor, and that the adrenal hormones mainly express their effect in crypt cells. It is proposed that this phenomenon may, in part, explain the reduction in calcium absorption which occurs in man after chronic glucocorticoid treatment.

The Temporal Distribution of the 1α,25-Dihydroxycholecalciferol Receptor in the Rat Jejunal Villus

Abstract: 1. The distribution of the 1α,25-dihydroxycholecalciferol receptor was studied in enterocytes isolated from the upper, mid and lower villus and crypt cells of the jejunum of normal and rachitic rats. 2. In all cell fractions a high-affinity receptor ( K D ⋍ 0.07 nmol/l) with a sedimentation coefficient of 3.5S was demonstrated. 3. In normal rats there was a 60% reduction in receptor numbers in crypt cells compared with the mid and upper villous cells. 4. Vitamin D deficiency led to a reduction in receptor numbers in all cell fractions (45% upper villus, 78% crypt cells). 5. The data are compatible with the concept of calcium absorption occurring in the differentiated villous cells and also account for the reduction in absorption in rachitic animals.

Crypt architecture of tonsilla lingualis in the monkey, Macaca fascicularis. A correlated light- and scanning electron-microscopic study.

Abstract: Crypts of the lingual tonsil were investigated in 10 male and female Macaca fascicularis by use of correlated light and scanning-electron microscopy. Counting of crypt openings provided an estimate of the total number of respective crypto-lymphatic units, which were found to range from 20 to 39. Crypt openings appeared in three distinct morphological varieties, i.e. circular, oval or slit-like. Tonsillar units existed individually or were arranged in a rosary fashion below a slit-like mucosal fold serving as a common exit. Although the crypt epithelium was generally non-keratinized, individual cells showing a surface pattern similar to that of the keratinized cells could be encountered. The crypt epithelium was frequently fragmented and showed heavy mononuclear cell infiltration and surface discontinuities, with lymphoid cells coming in contact with luminal contents. The crypt lumen either appeared as a simple epithelial invagination or existed as a complex, cavernous pouch with many blind-ending diverticula. The lumen contained a mixture of exfoliated epithelial cells, leucocytes and bacteria. The secretory ducts of the posterior lingual glands opened occasionally at various levels into the crypt lumina or independently to the exterior.

Comparison of tritiated thymidine and metaphase arrest techniques of measuring cell production in rat intestine

Abstract: Measurements of intestinal cell production at several sites throughout the gastrointestinal tract were compared using two different methods, namely tritiated thymidine to determine the uptake of tritium per unit weight of tissue (dpm/mg) and per microdissected intestinal crypt or stomach gland (dpm/crypt or gland) and the metaphase arrest technique, in the same group of rats. The metaphase arrest technique was employed to determine the crypt cell production rate per hour (CCPR). The dpm/crypt or gland of tritiated thymidene-derived tritium in microdissected intestinal crypts or stomach glands showed a good linear correlation (r=0.93) with CCPR which extrapolated through the origin. The dpm/mg wet weight of tissue showed a good linear correlation with CCPR (r=0.87) and dpm/crypt (r=0.97); however, neither of these relationships extrapolated through the origin. Instead there was a positive intercept of dpm/mg tissue which represented about 25–30% of the maximal tritium content of the intestine. This radioactivity in tissue had no counterpart in the crypts or glands and presumably reflected unbound tritium and tritium in cells which were located outside the epithelial compartment. The good linear correlation (r=0.93) between dpm/crypt and CCPR extended to the intestine of transected and 75% small bowel resected rats. Subsequent analysis of the times recorded for these procedures showed that determination of CCPR was faster by at least 25% than measurement of dpm/crypt. In conclusion, dpm/crypt but not dpm/mg tissue gave a valid estimate of intestinal cell production equivalent to measurement of CCPR. However, the metaphase arrest technique was faster, provided smaller relative errors, and gave a more direct measure of cell production and is therefore preferred.

Biosynthesis of intestinal microvillar proteins. Expression of aminopeptidase N along the crypt-villus axis.

Abstract: The expression of pig small-intestinal aminopeptidase N (EC 3.4.11.2) along the crypt-villus axis was studied in tangential sections of [35S]-methionine-labelled, organ-cultured explants. The only detectable molecular forms of aminopeptidase N along the crypt-villus axis were polypeptides of Mr 140 000 and 166 000, representing the enzyme in a transient and mature form respectively. The synthesis was at a very low level in the crypt region in experiments with labelling periods ranging from 10 min to 3 h. These findings indicate that crypt cells are not fully committed to the expression of aminopeptidase N, either in its mature or in any other immunoreactive molecular form. The expression of aminopeptidase N was markedly stimulated by dexamethasone (1 microgram/ml). During labelling periods of 3 h, dexamethasone caused an approximately threefold increase in the expression of the enzyme in the crypt cells and a moderate increase of about 20% in the villus cells. Whereas the latter can possibly be ascribed to a general protective effect of dexamethasone on villus architecture, these experiments indicate that crypt cells of mucosa from adult individuals exhibit the same sensitivity to glucocorticoids as does the intestinal epithelium during the prenatal and early postnatal phase.

Bivariate flow cytometric analysis of murine intestinal epithelial cells for cytokinetic studies.

Abstract: The heterogeneous nature of the small intestine and the lack of methods to obtain pure crypt populations has, in the past, limited the application of standard flow cytometric analysis for cytokinetic studies of the proliferating crypts. The authors describe a flow cytometric technique to discriminate crypt and villus cells in an epithelial cell suspension on the basis of cell length, and to measure the DNA content of the discriminated subpopulations. These data indicate that bivariate analysis of a mixed epithelial cell suspension can be used to distinguish mature villus cells, G/sub 1/ crypt cells, and S-phase crypt cells. In addition, continuous labeling studies suggest that the position of a cell on the cell length axis reflects epithelial cell maturity. The authors applied this flow cytometric technique to determine the cytokinetic nature of epithelial cells obtained by sequential digestion of the small intestine. 22 references, 4 figures, 2 tables.

Are there diurnal fluctuations in crypt length and crypt cell birth rate in the intestines of normal and carcinogen-treated rats?

Abstract: At eight time points over a period of 24 hours, crypt length (in cells) and crypt cell birth rate were measured by the stathmokinetic method with vincristine and evaluated at two sites in the small intestine and two in the colon in Wistar Porton rats. Normal animals were compared with animals which had received 24 injections, at weekly intervals, of the intestinal carcinogen 1,2-dimethylhydrazine. In the treated animals, crypts were significantly longer at sites prone to tumour formation but not at those sites known to be resistant to the effects of the carcinogen. In neither group of animals was there any significant fluctuation in mean crypt length over a 24 hours period. Crypt cell birth rates showed a considerable fluctuation. No difference was noted between normal animals and those treated with dimethylhydrazine and statistical analysis failed to confirm the presence of any true periodic fluctuation.

Morphological effects of transposing a segment of transverse colon into the ileum of the Holtzman rat.

Abstract: In order to determine if the rat colon is capable of adaptation when placed in another location within the intestinal tract and/or subject to different luminal contents, a 3 cm segment of transverse colon was transposed into the ileum. Sixteen days later, the animals were injected with tritiated thymidine (1 μCi/g body weight) and killed one hour later. Autoradiographs were analyzed for number of cells per crypt column, number of labeled cells per crypt column, position of labeled cells in the crypt column, and formation of Paneth cells or villi in the transposed colon. Proliferative activity of the epithelium was measured by isolating whole crypts and determining disintegrations per minute per crypt. Except for alterations in the positions of labeled cells, as determined by crypt profiles, no changes from normal were observed in any of the parameters measured. Hence, unlike the small bowel, the colon is refractory to the influences of a new environment.

Relationship between surviving clonogenic crypt fraction and animal lethality after cytosine arabinoside (Ara-C) exposure.

Abstract: We have measured animal morbidity and the fraction of clonogenic crypt cells following administration of several doses of Ara-C as an infusion over a 24 h period. A nonlinear relationship between reduction in crypt cell survival and Ara-C induced animal lethality was observed, indicating that factors other than crypt cell toxicity contribute to lethality in conventionally-maintained mice. A dose of 100 mg/kg Ara-C reduced the fraction of surviving clonogenic crypt cells to 7 × 10−3 without animal lethality. However, 300 mg/kg reduced crypt clonogenic cell survival only to 4× 10−3 while killing 50 percent of the animals. Maintenance of the animals on acid water before and after Ara-C treatment reduced animal lethality substantially. The magnitude of the reduction of clonogenic crypt cells was incompatible with S-phase specific toxicity as the only cytotoxic mechanism, and suggested that cell recruitment and crypt cell kill due to unbalanced growth are also operative during Ara-C infusion. In addition, the detection of a subpopulation of clonogenic crypt cells which was resistant to killing by Ara-C has important clinical implications and warrants further investigation. These results are substantially different than those found after radiation where, with high radiation doses, the fraction of clonogenic crypt cells decreases exponentially, and where a close relation between reduction in clonogenic crypt cell survival and animal lethality has been established.

Cointegrate formation during mobilization of nonconjugative plasmids by pAP42 plasmid for genetic transfer

Abstract: The excess of vitamin A, orally administered to young albino male rats (during 8 days, per os, in total dose of 400000 ME per rat) induced a considerable decrease in the number of mitoses in the small intestine crypt glands of both its distal and proximal parts. This treatment also led to changes in the intestine mucosa morphology (decrease of the crypt depth and number of epithelial cells, lining crypts) and to the loss of the RNA content gradient along the villus. It is concluded, that in rats the small intestine mucosa is an organ-target for vitamin A, and its excess induce the inhibition of enterocyte proliferation and impairment of their differentiation.