Number Of Villi Research Articles

Myoelectric activity and absorptive capacity of rat small intestinal isografts

The effect of transplantation on small intestinal absorption, digestive capacity, myoelectric activity, and morphology was assessed in inbred Lewis rats. Electrodes were sutured to the duodenum and isografted jejunoileum or to the native jejunoileum in controls. The frequency of migrating myoelectric complexes (MMCs) in the duodenum was 3.3 +/- 0.3/hr in controls and 1.8 +/- 0.4/hr in transplants (P < 0.05). MMC frequency in the jejunoileum was 5.1 +/- 1.3/hr in controls and 3.2 +/- 0.9/hr in transplants (P > 0.05). MMCs appeared to migrate from the duodenum to the jejunoileum 80 +/- 3% of the time in controls and 59 +/- 7% of the time in transplant rats (P < 0.05). Absorption in the transplanted jejunoileum demonstrated a 35-40% decrease in glucose and electrolytes absorption. Villus height and number of nuclei per villus was reduced. Intestinal length (dry) was 103 +/- 6 cm for controls and 51 +/- 3 cm for transplant rats (P < 0.05). Brush border sucrase activity was unchanged. We conclude that small intestinal isografts display similar myoelectric activity as controls, but the decreased absorptive capacity and villus height may require longer segments of intestine to be transplanted in order to support normal nutrition.

A Surgical Model to Increase the Intestinal Absorptive Surface: Intestinal Lengthening and Growing Neomucosa in the Same Approach

Despite numerous investigations short bowel syndrome (SBS) is still an unsolved clinical problem. The purpose of this study was to develop a new surgical approach that combines both intestinal lengthening and growing neomucosa. The operative principle is based on a longitudinal division of an intestinal segment antimesenterically and a formation of two intestinal tubes out of bowel halves anastomosing one cutting edge to the incised mucosal midline and the other to the antimesenteric side of the constructed first intestinal tube, so that a common wall between the two hemiloops was created which leads to grow neomucosa. This procedure was applied to 11 rabbits. The hemiloops and neomucosa were investigated for its feasibility and morphologic characteristics. Gross and microscopic examinations at 8 weeks revealed that all the intestinal tubes were viable and patent. No anastomotic leakage was present. In all animals, the serosal surfaces of the common walls were covered with neomucosa that resembles the mucosa of the existing intestine morphologically; there was no significant difference in villus height, villus width at base, crypt depth, number of villi per unit serosal length, villus surface, and villus surface per unit serosa. The growth of neomucosa was completely a result of epithelialization without any evidence of contraction. The quantity and rate of neomucosal growth seems uneffected by intestinal segment length. Finally a two times increase in intestinal length, whereas the diameter halved and a statistically significant increase (P< 0.001) in total villus surface via growing neomucosa was obtained. This model might be useful in the management of SBS when supported by clinical and functional investigations.

Cytokinetic and structural responses of the rat small intestine to riboflavin depletion

Abstract:The impaired absorption and metabolism of Fe seen in riboflavin defiaency is attributed, at least in part, to a hyperproliferative response in the small intestine, associated with an altered morphology. Studies were conducted in female weanling Wistar rats to explore further the effect of riboflavin deficiency on the cytokinetics and structure of the small intestine. Feeding a riboflavin-deficient diet for 8 weeks from weaning resulted in a significantly lower villus number, a significant increase in villus length and an increased rate of transit of enterocytes along the villi, compared with weight-matched controls. A second experiment focused on the 3 weeks after weaning and showed that riboflavin deficiency inhibits the increase in villus number observed in control animals over this period. We suggest that riboflavin deficiency induced at weaning impairs the normal increase in villus number and that prolonged deficiency leads to an adaptive increase in length of villi and depth of crypts.

Seasonal changes in gut morphology of the striped field mouse (Apodemus agrarius)

I studied seasonal changes in length and wet mass of the digestive tract and area of the mucosal surface of the small intestine in wild adult striped field mice (Apodemus agrarius). The length and mass of the gut varied with season in males but not females. The mucosal surface area of the small intestine was highly correlated with seasonal variations in the size of the alimentary tract. Changes in the surface area of the mucosa depended on changes in both villus size and the number of villi per unit area. The area of the intestinal mucosa varied during the year in both females and males, but unexpectedly, the mucosal surface area in females was significantly larger than in males only in autumn. Because gut size decreased toward late autumn, I suggest that late autumn was not a stressful period (i.e., because of low temperature or poor-quality food) for wild field mice. The decrease in gut parameters may have been an effect of declining metabolic requirements and completion of reproduction in late autumn.

Morphological changes in the rat small intestine in response to riboflavin depletion

Female Wistar rats were weaned onto a diet deficient in riboflavin and compared with weight-matched and ad lib.-fed controls. The effects of riboflavin deficiency on villus morphometry and enterocyte number on the villi in the upper small intestine were studied. Riboflavin depletion was associated with increased villus length and a proportional increase in the number of cell positions along the villi. The total DNA, RNA and protein contents in the intestinal mucosa were not significantly different between any of the groups. Villus hypertrophy in the absence of increased cell number in the small intestine suggests that villus number may be reduced in riboflavin deficiency. Riboflavin deficiency did not influence the number of mucus-producing goblet cells or the amount of mucosal glycoprotein in the small intestine. Impaired production of mucus appeared not to be involved in the structural and functional changes seen in riboflavin deficiency.

Studies on ethanol-induced subepithelial fluid accumulation and jejunal villus bleb formation. An in vitro video microscopic approach.

Jejunal intraluminal ethanol causes morphological and mucosal microvascular injury. The purpose of the present study was to understand the mechanism of the morphological alterations caused by ethanol without the influence of ethanol's effect on the microcirculation. Therefore, we have investigated the ethanol-induced morphological changes in the absence of blood flow (i.e., in the jejunum in vitro) and compared these changes with those reported to occur in the presence of microcirculation (i.e., in the jejunum in vivo). The mucosa of jejunal segments was exposed to a control solution and to solutions containing 0.8, 1.6, and 4.8% (w/v) ethanol, using a specially designed apparatus. The morphological response of the mucosa to these solutions was continuously examined employing a video microscopic technique, and the changes were morphometrically evaluated on subsequent playback of videotapes. Ethanol caused a concentration-dependent increase in the number of villi with subepithelial fluid accumulation, i.e., blebs, and a decrease in the height of the villus core (i.e., lamina propria). With 0.8 and 1.6% ethanol, the contracted core remained partially attached to the epithelium and the total villus height (villus core plus epithelial layer) decreased. With 4.8% ethanol, the villus core contraction was so rapid that the stroma fully separated from the epithelium. Thus, among other factors, the rapidity of the villus core contractions appears to play a role in the subepithelial bleb formation and in the appearance of the bleb. The ethanol-induced changes in vitro are similar to those reported to occur in the jejunum in vivo. Therefore, we conclude that the effect of ethanol on morphology is independent of its action on the microcirculation.

Structural and morphometric analysis of murine small intestine after indomethacin administration.

Indomethacin, a nonsteroidal anti-inflammatory drug, induces the formation of gastrointestinal ulceration both in experimental animals and in humans. A study of indomethacin-induced ulcers in the mouse showed that two doses of indomethacin, each administered subcutaneously at 85 mg/kg body weight, induced well-defined gastrointestinal ulcers in C57 mice, accompanied by inflammatory and vascular changes in the stomach and small intestine. Maximal damage was observed 20 h after the second dose of indomethacin. Morphometric analysis identified changes in all compartments of the small intestine. There was a marked reduction in the length of the small intestine, intestinal dilatation, a significant decrease in villous height, with the formation of subepithelial blisters or blebs within villi, and submucosal vascular dilatation. There was no change in the number of villi or of submucosal arterioles or in the total amount of muscle present in the wall of the intestine. The tissue changes identified in this study may have implications for gut function at specific periods during indomethacin treatment.

Caloric restriction perturbs the pituitary-ovarian axis and inhibits mouse mammary tumor virus production in a high-spontaneous-mammary-tumor-incidence mouse strain (C3H/SHN)

Dietary restriction (DR) retards aging and extends maximum life span. It is also known to decrease the incidence of hormone-dependent tumors. In the present investigation, we focussed primarily on the influence of DR on the pituitary-ovarian axis, and subsequently on gene expression of the mouse mammary tumor virus. F 1 females from the mating of SHN female and C3H male mice were used in this study, since these hybrids display a very high incidence of mouse mammary tumors. The mice weaned at 3 weeks were raised on either a calorically-restricted diet (DR: 50 kcal/week; N = 5) or on a control diet (C: 95 kcal/week N = 5) for 5 weeks. Three C57BL/6J Jcl ad libitum-fed female mice, 8 weeks of age, were used as reference animals since this strain has a very low incidence of mammary tumors. The mean cellular contents of prolactin (PRL) and growth hormone (GH) in the pituitary, as determined by immunohistochemistry, were found to be reduced in mice raised on the DR diet. The decrease in the mean cellular content of PRL (50% of the mean control value) was accompanied by a decrease in the number of lactotrophs (17% of the mean value of control diet mice). However, the decrease in cellular content of GH (53% of the mean control value) was not accompanied by a decrease in the number of somatotrophs (no. of somatotrophs in DR = 103% of mean control value). Histologically, ovaries from DR mice showed many growing and atretic follicles, with few corpora lutea. In contrast, both control-diet and reference (C57BL/6J Jcl) mice showed two or three corpora lutea per ovarian section. In accordance with this finding, DR mice had not established stable estrus cycles by 8 weeks of age, in contrast to both control-diet and reference mice. Since caloric restriction has been shown to decrease mammary tumor virus (MMTV) gene expression. MMTV production was investigated by electron microscopy to confirm the validity of our experimental conditions. In DR or reference C57BL/6J Jcl mice, MMTV particles were rarely found in the mammary gland samples, but were always found in samples from control mice. The development of mammary glands, as indicated by the number of villi or the development of the rough endoplasmic reticulum, was delayed in DR mice. Thus, it was concluded that caloric restriction decreases the number in lactrotrophs, inhibits ovulation and delays mammary gland development. The immature status is considered to be due to perturbations in the pituitary-ovarian axis by caloric restriction.

A correlation of permeabilities for passively transported compounds in monkey and rabbit jejunum.

Permeability measurements were conducted for a series of compounds using in vitro tissue sections from monkey and rabbit jejunum. Jejunal segments were stripped of serosal musculature and mounted in a diffusion-cell system, using previously described methods and equipment. Permeability determinations of radiolabeled compounds ranging over two orders of magnitude in molecular weight were conducted. For the compounds examined, the permeability of the rabbit jejunum was approximately twice that of the monkey. This was in contrast to the relationship implied by the stripped tissue thickness measurements of 0.92 and 0.83 mm for rabbit and monkey, respectively. An investigation of the size of the paracellular space in the jejunum was undertaken to account for this apparent discrepancy in tissue permeability. Scanning electron micrographs of intestinal sections revealed a similar packing density of cells between species; however, a difference was noted in the shape and number of villi per unit area. Comparative measurements of the paracellular volume in both species using mannitol and methoxyinulin as extracellular space markers further suggests that the paracellular junctions are similar in size but more numerous per unit area of rabbit jejunum than that of the monkey. In contrast to passively transported compounds, the active transport of D-glucose was greater in monkey jejunum compared to rabbit tissue segments. When active transport was inhibited by blockade of the sodium pump with ouabain, the passive component of D-glucose transport for both rabbit and monkey tissue was in agreement with the relationship demonstrated above for compounds which are solely transported by passive processes.

Ulcerative colitis in protracted remission. A quantitative scanning electron microscopic study.

Colonoscopic biopsies from 32 patients were studied at the ultrastructural level using a scanning electron microscope (SEM). Sixteen of the 32 patients had a previous diagnosis of total ulcerative colitis (UCR greater than 10 years) in protracted remission. The colonic mucosa was normal at endoscopic and histologic examinations (UCRN). The remaining 16 patients had normal colonic mucosa, but had an adenoma or an adenocarcinoma elsewhere in the colon. Several ultrastructural parameters were investigated, such as the number of crypts per area, the distance between the crypts, the outline of mucosal units, the number of mucous cells, the outline of absorptive cells, and the number of villi per area. Quantitative determinations of SEM structures (including measurements with an interactive digital image analyzer system; MOP 30, Zeiss Contron) were made. The results showed no significant differences between the various parameters (except for the number of crypts per area) between patients with UCRN and controls. The possibility of a total (or quasi-total) restitutio ad integrum of the colonic mucosa in certain patients with UCR is discussed. An international policy regarding the colonoscopic surveillance of patients with UCRN should be elaborated. It is suggested that the time interval between control colonoscopic biopsies in patients with UCRN should be increased substantially.

Adaptation of intestinal morphology in the temperature-acclimated carp, Cyprinus carpio L.

The effects of temperature and photoperiod acclimation upon the morphology of carp intestinal mucosa have been studied using morphometric techniques. Carp intestine showed an absence of anatomical regionalisation. There was a gradual reduction in the dimensions of villi along the tract. The decrease in the dimensions of the villi was greatest in the anterior half. Temperature acclimation had no effect on intestinal-somatic indices. Acclimation to 10 degrees C or 30 degrees C resulted in large differences in the dimensions of villi. Cold acclimation produced significant increases in mean villus height and breadth along the entire intestine. These villus shape changes resulted in a 58% increase in total mucosal surface area and a 102% increase in total volume of villi in cold-acclimated fish relative to warm-acclimated fish. Surface area of the unmodified intestinal tube increased with cold acclimation by 28%. The total number of villi remained unchanged by thermal acclimation. Because normalisation to a nominal surface area does not take account of the possibility of differentially developed mucosal surfaces in differently acclimated animals, experiments comparing transepithelial transport rates of differently-acclimated fish, using unstripped preparations, overestimates the differences in area-specific transport capacity.

Effects of exocrine pancreatic secretions on hyperthermic injury of rat small intestine.

The influence of the exocrine pancreatic secretions on development of small intestinal injury following localized hyperthermia was studied. In male Holtzman rats the excretory pancreatic ducts were occluded with metal hemostatic clips. An intraperitoneal injection of [3H]thymidine was given 3 weeks later. Three or 48 h after the injection a 10 cm segment of small intestine was exteriorized through a midline abdominal incision and heated at 38.0 degrees C, 42.5 degrees C, or 43.5 degrees C for 45 min. Intestinal damage was assessed 24 h after hyperthermia. The following four endpoints were used: histopathological injury score, the number of villi per intestinal circumference, the number of labelled epithelial cells in fixed areas of autoradiographic specimens, and incorporation of [3H]thymidine as determined by liquid scintillation counting. The correlation of results among the four methods of assessment was highly significant. The autoradiography data showed better correlation with both morphological parameters than the results of liquid scintillation counting. There was significantly less damage in heated segments from pancreatic duct-occluded animals than in segments from sham-operated controls. When hyperthermic injury was assessed morphologically the protection conferred by pancreatic duct occlusion was equivalent to lowering the temperature of heating by 1 degree C. It is concluded that morphological criteria may be superior to endpoints based on [3H]thymidine incorporation for assessment of hyperthermic injury in rat small intestine. Reducing the intraluminal pancreatic secretions appears to confer significant protection from small bowel injury after localized hyperthermia.

The development of the placental villus during normal pregnancy: morphometric data base.

The morphological structures of the terminal villus of the normal human placenta were evaluated morphometrically throughout pregnancy. The Videoplan (Kontron) system was used to measure a total of 6000 villi. The cross-sectional surface and circumference of the villus decrease continuously until the 28th week and remain stable thereafter. The cross-sectional surface, number, and circumference of villous vessels only increase until the 20th week. The relative degree of vascularization, however, increases further until 28th week together with a continuous decrease in villous size. Epithelial plates start to appear in the 18th to 20th week, and their development is essentially completed by the 28th week. According to the data presented, the development and differentiation of the placental villus are completed by the 28th week of gestation. Any further increase in nutritional capacity can only be provided by an increase in the number of villi and not their individual maturation. These results represent a morphometric data base for the quantification of retarded placental development in placental insufficiency.

Development of active and passive transport of bile acids in rabbit intestine

Previous studies have indicated that saturable, Na +-bile acid coupled transport is absent in the ileum throughout most of the suckling period and that the maturation of ileal bile acid uptake which occurs during weaning results primarily through an increase in functional bile acid carriers within the ileal brush border membrane. This study was undertaken in weanling and adult rabbits to establish the effect of maturation on the active ileal and passive jejunal and colonic uptake of 8 bile acids. The in vitro uptake of a range of concentrations of cholic (C), taurocholic (TC), glycocholic (GC), chenodeoxycholic (CDC), taurochenodeoxycholic (TCDC), glychochenodeoxycholic (GCDC), deoxycholic (DC) and taurodeoxycholic (TDC) acid was determined. Active ileal uptake of C, TC, GC, DC and TDC was greater in adult that in weanling animals, whereas uptake of CDC, TCDC and GCDC was similar in both groups. The relative permeability for passive uptake of bile acids into the jejunum and colon was similar in young and adult rabbits. Jejunal mucosal surface area was similar in the two groups, but was greater in the ileum in the adult than in the weanling rabbits due to an increase in villus height, width, and number of villi per unit serosal length. However, the age-associated differences in active bile acid uptake were not explained simply on the basis of these differences in ileal mucosal surface area or the concentration of bile acids in the intestinal lumen. Thus, maturation of the rabbit from weanling to adulthood does not influence the relative passive permeability of the jejunum or colon to bile acids, but does increase active ileal uptake of conjugated and unconjugated cholic acid and deoxycholic acid, but not chenodeoxycholic acid

Effects on the fetal rat intestine of maternal malnutrition and exposure to nitrofen (2,4-dichlorophenyl-p-nitrophenyl ether).

The effects of maternal protein-energy malnutrition and exposure to nitrofen on selected aspects of intestinal morphology and function were studied in the fetal rat. Pregnant rats were fed, throughout gestation, diets containing 24% or 6% casein as the sole source of protein. Reduced total food intake produced protein-energy malnutrition (PEM). Each diet group was divided in half and gavaged with either 12.5 mg nitrofen in corn oil/kg/day or corn oil carrier only from days 7 to 21 of gestation. Body weight, intestinal weight, length, and diameter were measured as were villus length (VL), villus width (VW), and number of villi per length of intestine (VMM). Protein (horseradish peroxidase) and lipid absorption were studied histochemically. Lactase and dipeptidase activities were determined in proximal, medial, and distal thirds of the intestine. Results showed that the restricted maternal diet resulted in reduced fetal body weight (BW), intestinal weight (IW) and length (IL), reduced IW/BW and IW/IL ratios, VH, and VMM. The VW was reduced only in the distal third. Protein and lipid absorption were unaffected. Lactase and dipeptidase activities were reduced. Maternal nitrofen exposure resulted in reduced body weight, intestinal size, and lipid absorption, with some evidence of interaction with the diet effects on enzyme activities. It is concluded that effects of maternal malnutrition were extensive, but that nitrofen exposure, at this dosage level, is not likely to contribute to the postnatal fetal mortality rate in either adequately nourished or malnourished rats.

Degeneration of the alimentary tract in sexually maturing European Anguilla anguilla (L.) and American eels Anguilla rostrata (LeSueur)

Gut morphology was examined in untreated and artifically matured European and American eels. In both species there was a decrease in gut size and gut muscle thickness with increasing sexual maturity. Hormone-treated, fully mature eels displayed advanced degeneration of the muscle layers. Total muscle thicknesses decreased from as high as 740 μm in sexually immature eels to less than 100 μm in sexually mature eels. Numbers of villi also decreased with maturity, with mature fish having relative lumenal circumferences that were less than half of those of immature fish. Epithelial structure changed with maturation and the number of mucous cells decreased. It is suggested that the degenerative changes are caused by elevated cortisol levels. Possible effects of gut changes on osmoregulation in seawater are discussed.

Three-dimensional structure and cell kinetics at different sites of rat intestinal remnants during the early adaptive response to resection

In this study the early phase of the morphological adaptation of rat ileum after a proximal resection of 60% has been studied using microdissection and cell labelling techniques. Resected rats and sham-operated controls were killed 2, 4, 6, 10 and 12 days after surgery. Intraperitoneal injections of 3H-thymidine were carried out 24 or 12 h prior to sacrifice. In the latter groups mitotic arrest was achieved by vincristine. A stereo-microscope was used to measure and calculate the following parameters: intestinal diameter; villus: height, width, breadth at base and apex, surface, enterocytes per 100 micrometers length, cell pool, number of villi and absorptive surface per mm2 serosal area; crypt: length, enteroblasts per 100 micrometers length and per column, cell columns and mitoses per crypt, cell pool, crypts, and mitoses per unit serosal area; cell kinetics: migration rate, villus transit time. To test the influence of treatments, postoperative time course and the location of the intestinal segment and their possible interactions, factorial analyses of variance were carried out on the parameters investigated. The main findings, demonstrated for the first time, were: 1. An increase in the villus surface which was achieved by proportional enlargement of villus geometry; 2. This increase in the villus surface led to an enlarged absorptive surface per unit serosal area; 3. A reduction of villus transit time of the individual enterocyte; 4. A most pronounced magnitude of adaptative response in the proximal remnants which was gradually diminished in aboral direction, and 5. A sequential course of adaptative response of the various crypt parameters investigated.

Quantitative histomorphometric study of the jejunal mucosa in chronic alcoholics.

Jejunal suction biopsies of 18 chronic alcoholics (alcohol intake of more than 100 g of ethanol per day for several years) and 10 nonalcoholic control subjects were analyzed quantitatively using the microdissection technique described by Clarke. Both groups were comparable concerning age, body weight and sex. The duration of alcohol withdrawal in the alcoholics before the biopsy was taken ranged from 2 to 7 days. The mean number of villi and surface per villus was slightly lower in the jejunum of the alcoholics. The mucosal surface per mm2 was significantly lower in the latter group when compared to the controls (p less than 0.005). The ratio of the number of crypts per villi was increased in the alcoholics (p less than 0.05). Histological evaluation revealed a more than twofold increase in the number of interepithelial mononuclear cells (p less than 0.005), while the number of epithelial cells/100 microns of villous mucosa and the mean height of the epithelial cells were comparable in both groups.

Scanning electron microscopy, autolysis, and irradiation as techniques for studying small intestinal morphology

Examination of autolysed control mouse small intestine using scanning electron microscopy has revealed details of the connective tissue components of the mucosa. The cores of the villi are seen collapsed across the intervillous basin. Crypts of Lieberkuhn are seen as tubular channels stretching down from the intervillous basin. Sometimes the crypts are split in two by a connective tissue septum. The mouths of the crypts of Lieberkuhn are, in general, arranged in double rows between the single rows of villi. The ratio of number of crypts to numbers of villi was calculated as 5.01:1. This is close to the figure of 4.53:1, as quoted by Smith & Jarvis (1980) who used differential interference contrast microscopy to investigate the crypt to villus ratio. After radiation, the severe drop in the number of crypt mouths can be clearly seen by the combination of autolysis and scanning electron microscopy: the rows of crypt mouths between the villi have been lost, and many crypt mouths have been occluded by stromal tissue. The arrangement of the crypt mouths and the observation of mucosal abnormalities after irradiation have led to the postulation that cells leaving the crypt mouths move in a spiral manner towards and then up the villous surface: this postulated movement might imply an asymmetry in some properties of enterocytes. The use of scanning electron microscopy in conjugation with autolysis and irradiation has thus forced a critical re-examination of the relationships between crypts and villi.

Early postnatal development of the intestine in progeny of protein-deprived rats.

Development of the small intestine was studied in newborn, and 4-, 8-, and 12-day-old young of rats fed diets, during gestation, containing 24 or 4% casein as the source of protein. Newborn prenatally protein-deprived rats had shorter, narrower intestines, reduced numbers of villi per unit length, shorter villi, and reduced numbers of absorptive cells and crypt cells. These differences had disappeared by the age of 12 days in adequately fed pups that had survived to that age.