Individual Villi Research Articles

A wireless endoscopy capsule suitable for imaging of the equine stomach and small intestine.

BackgroundCapsule endoscopy offers a new method for visualization of the gastrointestinal mucosa in horses where other imaging technologies have diagnostic limitations.ObjectivesTo (1) test the feasibility of using this novel endoscopy capsule to visualize intestinal mucosa in horses, including an objective assessment of image quality, (2) assess how changes in preadministration preparation affect the transit time and the amount of gastrointestinal mucosa visualized, and (3) describe intestinal mucosa lesions in healthy horses.AnimalsFive healthy adult horses.MethodsThree protocols were used in a crossover study design. Protocols varied in time fasted, amount of oral fluid administered, and exercise. Manure was radiographically inspected for capsule recovery. Percentage of visible gastrointestinal mucosa was objectively assessed.ResultsDetailed images of the gastrointestinal mucosa were recorded with all 3 protocols, including images of the pylorus, major duodenal papilla, individual villi, and ileocecal junction. Visualization of large intestinal mucosa was poor. Interobserver agreement on image quality was excellent. Capsule administration after feed withholding for 24 hours provided the greatest percentage of visible mucosa in the stomach and small intestine. Total transit time to capsule excretion was 6.5 (3‐8.75) days. Of 15 capsules administered, 3 were not recovered. Lesions visualized included mucosal erosion, ulceration and hemorrhage, areas of thickened mucosa, and evidence of parasitism.ConclusionsThis novel endoscopic capsule appears safe, practical, and noninvasive in horses; however, variability in capsule excretion time must be taken into account for clinical application.

Villification: how the gut gets its villi.

The villi of the human and chick gut are formed in similar stepwise progressions, wherein the mesenchyme and attached epithelium first fold into longitudinal ridges, then a zigzag pattern, and lastly individual villi. We find that these steps of villification depend on the sequential differentiation of the distinct smooth muscle layers of the gut, which restrict the expansion of the growing endoderm and mesenchyme, generating compressive stresses that lead to their buckling and folding. A quantitative computational model, incorporating measured properties of the developing gut, recapitulates the morphological patterns seen during villification in a variety of species. These results provide a mechanistic understanding of the formation of these elaborations of the lining of the gut, essential for providing sufficient surface area for nutrient absorption.

Characterization of Androgenetic/Biparental Mosaic/Chimeric Conceptions, Including Those With a Molar Component

Recent studies have demonstrated the value of ancillary techniques, including p57 immunohistochemistry and short tandem repeat genotyping, for distinguishing hydatidiform moles (HM) from nonmolar specimens and for subtyping HMs as complete hydatidiform moles (CHM) and partial hydatidiform moles (PHM). With rare exceptions, CHMs are p57-negative and androgenetic diploid; partial hydatidiform moles are p57-positive and diandric triploid; and nonmolar specimens are p57-positive and biparental diploid. Androgenetic/biparental mosaic/chimeric conceptions can have morphologic features that overlap with HMs but are genetically distinct. This study characterizes 11 androgenetic/biparental mosaic/chimeric conceptions identified in a series of 473 products of conception specimens subjected to p57 immunohistochemistry and short tandem repeat genotyping. Fluorescence in situ hybridization was performed on 10 to assess ploidy. All cases were characterized by hydropically enlarged, variably sized and shaped villi. In 5 cases, the villi lacked trophoblastic hyperplasia, whereas in 6 there was a focal to extensive villous component with trophoblastic hyperplasia and features of CHM. The villi lacking trophoblastic hyperplasia were characterized by discordant p57 expression within individual villi (p57-positive cytotrophoblast and p57-negative stromal cells), whereas the villous components having trophoblastic hyperplasia were uniformly p57-negative in both cell types. Short tandem repeat genotyping of at least 2 villous areas in each case demonstrated an excess of paternal alleles in all regions, with variable paternal:maternal allele ratios (usually >2:1); pure androgenetic diploidy was identified in those cases with a sufficiently sized villous component having trophoblastic hyperplasia and features of CHM. Fluorescence in situ hybridization demonstrated uniform diploidy in 7 cases, including 4 of 5 tested cases with trophoblastic hyperplasia and 3 of 5 cases without trophoblastic hyperplasia. Two cases without trophoblastic hyperplasia had uniformly diploid villous stromal cells but 1 had triploid and 1 had tetraploid cytotrophoblast; 1 case with trophoblastic hyperplasia had uniformly diploid villous stromal cells but a mixture of diploid, triploid, and tetraploid cytotrophoblast. In 3 cases with a CHM component, persistent gestational trophoblastic disease developed. These results indicate that androgenetic/biparental mosaic/chimeric conceptions are most often an admixture of androgenetic diploid (p57-negative) and biparental diploid (p57-positive) cell lines but some have localized hyperdiploid components. Recognition of their distinctive p57 expression patterns and genotyping results can prevent misclassification as typical CHMs, PHMs, or nonmolar specimens. The presence of androgenetic cell lines, particularly in those with a purely androgenetic CHM component, warrants follow-up because of some risk of persistent gestational trophoblastic disease.

Ketotifen abrogates local and systemic consequences of rat intestinal ischemia–reperfusion injury

Mast cell-derived vasoactive and pro-inflammatory mediators, particularly histamine, might contribute to local tissue damage and multiorgan dysfunction induced by intestinal ischemia/reperfusion (I/R). The purpose of the present study was to evaluate the effects of the mast cell stabilizer, ketotifen, on leukocyte adhesion within, and tissue leakage from the mucosal villous microcirculation after intestinal I/R. Superior mesenteric arteries of untreated and ketotifen-pretreated (1 mg/kg orally twice daily for 3 days, and 90 min prior to ischemia) Piebald-Viral-Glaxo (PVG) rats were clamped for 30 min (n = 12 per group; sham operated controls n = 12). Mucosal surfaces of exteriorized ileal segments were visualized, and leukocyte adherence in, and macromolecular leakage (MML) from individual villi were followed for 2 h after clamp removal using in vivo microscopy. Blood pressure and heart rate were monitored, and lung tissue damage was assessed by histology. Ten untreated animals subjected to intestinal I/R failed to survive the reperfusion period, leukocyte adhesion (P < 0.001) and MML (P < 0.001) were increased at all time-points and blood flow stasis eventually ensued. In contrast, all ketotifen-pretreated I/R animals survived the duration of the study. Ketotifen abrogated I/R-induced leukocyte adherence within the villus mucosal capillaries and supplying arterioles and largely prevented pulmonary injury, yet surprisingly had no effect on intestinal vascular leakage. This is the first study to demonstrate that ketotifen is a powerful inhibitor of I/R-induced leukocyte adhesion and can prevent localized and reduce remote organ damage after intestinal I/R injury. However, its effects are manifested in the absence of any influence on intestinal I/R-induced vascular leakage.

Effects of hypothermia and rewarming on the mucosal villus microcirculation and survival after rat intestinal ischemia-reperfusion injury.

To determine the effects of hypothermia and rewarming on changes in the villus microcirculation induced by intestinal ischemia-reperfusion (I/R). The small intestine is extremely sensitive to I/R injury, and although hypothermia can reduce cellular injury, its capacity to influence the villous microcirculation after intestinal I/R is unclear, especially after the return to normothermic conditions. Core body temperature of PVG rats was maintained at either 36 degrees to 38 degrees C (n = 12) or 30 degrees to 32 degrees C (n = 24) and then subjected to 30 minutes of intestinal ischemia. A subgroup of hypothermic animals (n = 12) were returned to normothermic conditions 120 minutes after clamp removal. The mucosal surface was visualized in an exteriorized ileal segment and macromolecular leak (MML) and leukocyte adhesion were monitored using in vivo microscopy (n = 6 in each group). MML from individual villi and numbers of adherent leukocytes within villi were determined for 2 to 4 hours after clamp removal. Heart rate and mean blood pressure were monitored in all animals. Control animals underwent sham surgery (n = 12). Ten of 12 normothermic animals failed to survive the reperfusion period, whereas all hypothermic animals and 11 of 12 of the hypothermic animals that were returned to normothermic conditions survived. MML was significantly increased in all animals subjected to I/R, although leakage was more marked in animals subjected to continuous normothermia. Enhanced leukocyte adhesion and decreased blood flow were observed only in normothermic animals. Hypothermia might prove to be an effective strategy for preventing adverse side effects in clinical settings in which intestinal I/R can be predicted.

Effects of FK409 on intestinal ischemia-reperfusion injury and ischemia-induced changes in the rat mucosal villus microcirculation.

The small intestine is extremely sensitive to ischemia-reperfusion (I/R) injury and a range of microcirculatory disturbances contribute to tissue damage. Nitric oxide (NO) seems to be involved in tissue protection after I/R injury. This study therefore assessed the effects of the NO donor, FK409, on intestinal I/R injury and changes induced in intestinal microcirculation. PVG rats were subjected to 30-min intestinal ischemia with a subgroup of animals receiving FK409 (10 mg/kg i.v.) 30 min before ischemia and 30 min postreperfusion. Controls underwent sham surgery. The mucosal surface was visualized via an incision made in an exteriorized ileal segment and FITC-BSA or acridine orange was used to quantitate macromolecular leak (MML) and leukocyte adhesion, respectively. MML from, and numbers of adherent leukocytes within, individual villi were determined every 15 min for 2 hr after removal of the vessel clamp. Heart rate and mean blood pressure (mBP) were monitored throughout the experiment. Eleven of 12 untreated animals subjected to intestinal I/R injury failed to survive the 2 hr reperfusion period, whereas all 12 FK409-treated animals survived. MML and leukocyte adhesion were increased in untreated animals (P<0.001), and blood flow stasis eventually ensued. Although FK409 decreased mBP (P<0.001), MML and leukocyte adhesion were significantly (P<0.001) reduced, and villus blood flow was maintained throughout the observation period. FK409 prevented mortality after intestinal I/R, significantly reduced leukocyte adhesion, and maintained blood flow after intestinal ischemia and may therefore be of value in reducing tissue damage and improving outcome after small bowel transplantation.

Phenotype of the Endothelium in the Human Term Placenta

The placental endothelium contributes to regulating transplacental exchange and maintaining the immunological maternofetal barrier. We characterized the endothelial phenotype in human normal term placentae with a panel of antibodies to endothelial antigens using a standardized immunofluorescence method. Placental endothelium strongly expressed vWF, PAL-E, H-antigen, thrombomodulin, PECAM-1, CD34, CD36, ICAM-1, CD44, thy-1, A10/33-1, VE-cadherin, caveolin-1 and HLA-G, whereas occludin, claudin-1, eNOS, angiotensin converting enzyme (ACE), ICAM-2, endoglin and integrin-αθβ3were weakly expressed. PGI2synthase, tissue factor, E-selectin and VCAM-1 were not detected. Some antigens were heterogenously expressed along the vascular tree or within individual villi. Expression of ACE, eNOS, vWF, P-selectin, E-selectin, integrin αvβ3and endoglin was stronger in the maternal decidual vessels, while PECAM-1, CD44, thy-1 and caveolin-1 expression was stronger in fetal vessels. Some endothelial markers were present in trophoblasts and stroma. Endothelial proliferation was apparent in mature intermediate and terminal villi. There was limited inflammatory response to TNFα in explants, characterized by upregulation of vWF, P-selectin, PECAM-1 and CD44, downregulation of thrombomodulin, but no increase in ICAM-1 expression, nor induction of E-selectin, VCAM-1 or tissue factor. These patterns of heterogeneity, proliferative activity and inflammatory activation may underlie the specific physiological roles of the placental endothelium.

Focal reduction of villous blood flow in early indomethacin enteropathy: a dynamic vascular study in the rat

Background—Oral indomethacin causes villous shortening, microvascular damage, and distortion, which might induce mucosal ischaemia and necrosis.Aims—In order to determine the early events in indomethacin induced jejunal injury we examined the...

Electron Microscopic alterations in the fourth ventricle choroid plexus of rabbits after cyclophosphamide and mitomycin-C treatment

Cyclophosphamide and mitomycin-C have withstood the test of time for the treatment of many human neoplasms. While desirable results are achieved with their use, severe untoward toxic effects do occur in many body organs. Choroid plexus damage in the brain, varying from severe odema and necrosis of individual villi to haemorrhagic infarcts, are reported by Levine and Sowinski (1973) and Wenk et al (1979) after cyclophosphamide administration in rats. These authors noticed the choroid plex us of the fourth ventricle most susceptible for the drug injury. Separate groups of adult male and female rabbits were given single intraperitoneal injections of cyclophosphamide (200mg/kg) and mitomycin-C(0.1 mg/kg). After 48hrs, the control and treated animals were anaesthetized by using 30mg/kg sodium pentobarbital. The fourth ventricle choroid plexus was fixed in situ with buffered Karnovsky (1965) fixative (pH 7.3). After post-fixation in 1 per cent osmium tetroxide the tissues were processed for convential transmission electron microscopy.

Visualization of the mucosal villi on double-contrast barium studies of the small intestine by using a high molecular fraction of guaran

Guaran is a water-soluble polysaccharide from the seed endosperm of Cyanopsis tetragonolobus. A high molecular fraction of guaran, when added to barium, enhances barium coating of the intestinal mucosa. This study reports its use to demonstrate the mucosal villi of the small intestine during double-contrast barium examination in the rat and in the human. In the animal model, individual villi were identified surrounded by pools of barium. In the human, a granular pattern caused by the villi was seen. Individual villi were visible with high-definition radiography. This was confirmed by microscopic studies of biopsy specimens in which the villi were shown to have the same diameters as the structures seen on high-definition radiography.

Selective effects of graft-versus-host reaction on disaccharidase expression by mouse jejunal enterocytes.

Graft-versus-host reaction (GvHR) was induced in neonatal mice to produce crypt hyperplasia with and without stunted villi. Lactase activity was measured along individual villi of control and GvHR mice using quantitative cytochemistry. Lactase activity increased in control mice as enterocytes migrated over the lower part of the villus. This increase was followed by a period when lactase activity remained approximately constant. Effects produced by GvHR on this normal profile of development included an extension of the distance on the villus over which enterocytes could continue to increase lactase activity, a reduction in the time needed for an enterocyte to express lactase activity at maximal rate, and an overall decrease in the maximal lactase activity expressed by mature enterocytes. These effects have been quantified by fitting logistic curves to the experimental data. Parallel biochemical analyses of intestinal homogenates showed sucrase, isomaltase, trehalase and maltase activities to increase markedly 7-8 days after the injection of parental spleen cells. Attention is drawn to similarities between these results and steroid induced precocious development of intestinal function in neonatal mice.

Histogenesis of the mouse jejunal mucosa, with special reference to proliferative cells and absorptive cells.

The histogenesis of the mouse jejunal mucosa and distribution of cells capable of proliferation were studied by scanning and transmission electron microscopy and light microscopic autoradiography using 3H-thymidine. Villous primordia were found to commence their development as mucosal ridges on day 15 of gestation. Individual villi are identifiable on day 16 of gestation. Some villi reach their adult height in the neonate, while the rest gradually become longer during postnatal development. Epithelial cells lining the entire mucosal surface are undifferentiated and proliferative by day 15 of gestation. On day 16 of gestation, cells lose their proliferative capability at the upper part of the high villi, while cells lining the lower part of the villi and intervillous region remain undifferentiated as well as proliferative. As the crypt develops during postnatal development, undifferentiated proliferative cells are restricted in it, coming to reside in the lower two thirds of the crypt by day 28. The fine structural differentiation of absorptive cells starts at the upper part of villi on day 16 of gestation. The apical tubular system develops during the perinatal period. Large vacuoles, many lysosomes and lipid globules appear in suckling mice. The cells show the typical morphology of the absorptive cells by postnatal day 21. Undifferentiated proliferative cells show only little change during development: cytoplasmic organelles increase slightly and small apical granules appear during postnatal development.

Three-Dimensional Organization of Lymphatics and their Relationship to Blood Vessels in Rabbit Small Intestine. A Scanning Electron Microscopic Study of Corrosion Casts

Casts of small intestinal blood vessels and lymphatics in the rabbit were made with methacrylate and observed under a scanning electron microscope (SEM). In casting the lymphatics, a specially diluted low viscosity medium was injected intraparenchymally into the intestinal submucosa. This parenchymal injection allowed good reproduction of fine lymphatics, including the initial lacteals in the villi. The central lacteals were completely surrounded externally by the subepithelial blood capillary networks of the intestinal villi. Individual villi in the lower intestine contained only one central lacteal that drained through a thin lymphatic in the glandular layer into the submucosal lymphatic plexus. Villi in the upper small intestine were broader than those in the lower small intestine, and contained two to five lacteals. They anastomosed with each other at the villous base and formed a markedly expanded sinus. The cast submucosal lymphatics frequently showed constrictions strongly suggestive of valves. It was constantly observed that well-developed lymphatics in the submucosa ran in pairs and held an arteriole or artery between them. This close association of the lymphatics with arteries suggests that arterial vasomotion might provide an important hydrodynamic energy source for lymph formation and transport.

Hyaluronate Synthesis by Synovial Villi in Organ Culture

Individual canine synovial villi were used to establish short-term synovial organ cultures. These villi incorporated 3H-glucosamine into highly-polymerized 3H-hyaluronic acid (3H-HA), which was the only 3H-glycosaminoglycan identified in the culture medium. Some 3H-HA, and larger amounts of other 3H-glycosaminoglycans, were recovered from cultured tissues. Culture medium 3H-HA content was proportional to the surface area of cultured villi. Organ cultures of nonvillous synovium were compared with villi; nonvillous cultures synthesized less 3H-HA per mm2 of their synovial intimal surface than villi. These cultures complement cell culture techniques for in vitro studies of synovial lining cell function.

Measurements of intestinal villi non-specific and ulcer-associated duodenitis-correlation between area of microdissected villus and villus epithelial cell count.

Measurements of villus height, villus area, together with counts of epithelial cells in individual villi, were performed on endoscopic duodenal biopsies from five groups of patients: controls, ulcer-associated duodenitis, mild and severe non-specific (non-ulcerative) duodenitis, cimetidine healed ulcer-associated duodenitis and cimetidine healed non-specific duodenitis. The objectives of the study were two-fold: to establish if epithelial cell count correlated with simpler measurements of villus height or area; and to compare the findings in ulcer-associated and in non-specific duodenitis. Villus area correlated well with epithelial cell count per villus (r = 0.96); villus height correlated less well (r = 0.66). When compared with controls, there was a significant decrease in the epithelial cell count per villus in ulcer-associated and severe non-specific duodenitis, but this was confined to the visually inflamed area of the duodenal bulb. After healing of inflammation with cimetidine villus height, area, and epithelial cell count returned to values similar to those in controls. This study confirms that the effects of ulcer-associated and severe non-specific duodenitis on duodenal villi are identical.

Eimeria dispersa, E. adenoeides, and E. meleagrimitis: Intestinal Mucosal Disruption in Turkeys as Seen with Scanning Electron Microscopy

Tissues from the digestive tract of turkeys infected with Eimeria dispersa, E. adenoeides, or E. meleagrimitis were compared with tissues from uninfected controls as seen with light microscopy (LM) and scanning electron microscopy (SEM). Six regions were examined--duodenum, jejunum, ileum, cecal neck, cecal pouch, and large intestine. Although LM showed large numbers of E. dispersa in the epithelial cells, SEM usually showed little mucosal disruption. Occasionally the surface of duodenum and jejunum, as seen with SEM, was convoluted and disrupted. In one bird, some parasite-induced damage was found with either LM or SEM in the duodenum and jejunum of turkeys given E. adenoeides oocysts. Although LM showed parasites in the rest of the digestive tract of all E. adenoeides infected birds, SEM showed only a localized sloughing of the mucosa in the cecal pouch. The most extensive damage to the villar surface was caused by E. meleagrimitis. Infections often disrupted the villar tips, especially in the small intestine and cecal neck. Localized areas of pitting were often found on individual villi. All 3 species produced oocyst extrusion sites, especially in the ileum and the ceca.

Morphological analysis of denudation of the villi in the intestinal form of acute radiation sickness

Light and electron microscopy were applied to the study in sexually mature rats and mice of the areas of the duodenum, jejunum and the ileum 3-4 days after the irradiation in doses of 1000, 1500, 7000 and 15 000 R. Paraffine mucosal sections of the small intestine showed denuding of the stroma of individual villi. However, a study of the thin and semithin epon sections by light microscopy and of the ultrathin ones--by electron microscopy showed the villi to be always covered with enterocytes, whose cytoplasm was overloaded with lipid droplets and almost structureless. Thus, during the enteric form of acute radiation sickness there was no vital denuding of the villi, and the presence of such on paraffine sections served as the result of inadequate treatment of the material.

Surface ultrastructure of tissue cultured keratinocytes

The surface ultrastructure of human epidermal keratinocytes was examined by the thin metal replication of tissue cultured keratinocytes. The cell surface ultrastructure of a large number of keratinocytes at various stages of maturation could best be observed in mono- or thin-layer culture. Young premature keratinocytes (basaloid cells) were found to bear numerous slender villi at the advancing border as well as on the cell surface. These villi branched frequently. As cells matured to become Malpighian-like cells, the number of villi diminished and individual villi became shorter. Two or three villi emerged from one common stem. Completely keratinized cells appeared as polygonal scalelike cells usually situated on top of villi-bearing cells. These cells bore few or no surface villi but the surface was covered with ridges and furrows. Fibroblasts in the same culture showed a number of threadlike villi at the periphery but few on the surface.

Zur Quantifizierung der diabetischen Reifungsstörung der Plazenta

An attempt has been made to demonstrate the feasibility of quantitating by light microscopy and histoplanimetry the pathology of placental maturation associated with maternal diabetes mellitus. The size of chorionic villi, the development of chorionic vessels, stroma edema, and the distribution of these findings were used as criteria to assess the degree of the abnormality. In addition, the size of individual villi and the distribution of these villi over areas of known size were estimated. The results of these methods coincided in 72% of 25 cases thus studied. The advantages and disadvantages of both methods were evaluated. For the correlation of placental alterations on the one hand and of maternal and fetal pathology on the other, a quantitative assessment of placental maturation appears urgently required.

Choroid plexitis produced in rats by cyclophosphamide.

High doses of the alkylating drug, cyclophosphamide, injured the choroid plexuses of the rat. The lesion was characterized by severe edema, hemorrhage, and slight, focal leukocytic infiltration. This progressed to necrosis of individual villi and occasionally to hemorrhagic infarction of an entire plexus. The plexus of the fourth ventricle was more susceptible than the others and a similar lesion occurred in the ciliary processes of the eye. This drug-induced plexitis may prove useful for investigation of function and topographic specialization among the several choroid plexuses.