Density Of Villi Research Articles

Post-natal Growth of the Gastrointestinal Tract of the Siberian Hamster: Morphometric Analysis

Post-natal growth of the gastrointestinal tract of the Siberian hamster was studied in newborn and 3-, 7-, 14-, 21-, 42- and 90-day-old animals. Morphometric measurements and calculations were carried out: length and internal surface of gastrointestinal tract segments, size (height, width, surface) and density of villi as well as allometric growth rate of the length and internal surface of the segments with respect to the body mass. The fastest growth rate of the gastrointestinal tract segments was noticed during the first 3 days of the post-natal life. Nevertheless, significant regional differences in their growth rate were found. The increase in the length and internal surface of the large intestine was fastest, while the smallest increase was observed in the oesophagus. All segments of the gastrointestinal tract except oesophagus exhibited a positive allometric relationship to the body mass from birth till final weaning, whereas during the post-weaning period, the increase was isometric. Thus, at birth, the gastrointestinal tract segments were relatively smaller compared with those observed in adults, but then, the gastrointestinal tract grew faster than the rest of the body and reached its adult proportions just before the transition to solid food. Most probably, reaching the adult structure of the gastrointestinal tract before the final weaning is an essential condition for the proper growth of an organism after the weaning.

Effect of growth hormone, hyperbaric oxygen and combined therapy on the gastric serosa

To investigate the role of growth hormone (GH), hyperbaric oxygen therapy (HBOT) and combined therapy on the intestinal neomucosa formation of the gastric serosa. Forty-eight male Wistar-albino rats, weighing 250-280 g, were used in this study. The rats were divided into four groups (n = 12): Group 1, control, gastric serosal patch; Group 2, gastric serosal patch + GH; Group 3, gastric serosal patch + HBOT; and Group 4, gastric serosal patch + GH + HBOT. Abdominal access was achieved through a midline incision, and after the 1-cm-long defect was created in the jejunum, a 1 cm × 1 cm patch of the gastric corpus was anastomosed to the jejunal defect. Venous blood samples were taken to determine the insulin-like growth factor 1 (IGF-1) and insulin-like growth factor binding protein 3 (IGFBP-3) basal levels. HBOT was performed in Groups 3 and 4. In Groups 2 and 4, human GH was given subcutaneously at a dose of 2 mg per kg/d for 28 d, beginning on the operation day. All animals were sacrificed 60 d after surgery. The jejunal segment and the gastric anastomotic area were excised for histological examination. The inflammatory process, granulation, collagen deposition and fibroblast activity at the neomucosa formation were studied and scored. Additionally, the villus density, villus height, and crypt depth were counted and recorded. The measurements of villus height and crypt depth were calculated with an ocular micrometer. New vessel growth was determined by calculatingeach new vessel in a 1 mm(2) area. In the histological comparison of groups, no significant differences were observed between the control group and Groups 2 and 3 with respect to epithelialization, granulation, fibroblastic activity and the inflammatory process, but significant differences were present between the control group and all others groups (Groups 2-4) with respect to angiogenesis (P < 0.01) and collagen deposition (P < 0.05, P < 0.01). Significant differences between the control group and Group 4 were also observed with respect to epithelialization and fibroblastic activity (P < 0.01 and P < 0.05, respectively). There were significant differences in villus density in all of groups compared with the control group (P < 0.05). Crypt depth was significantly greater in Group 4 than in the control group (P < 0.05), but no other groups had deeper crypts. However, villus height was significantly longer in Groups 2 and 4 than in the control group (P < 0.05). The comparison of groups revealed, significant difference between control group and Groups 2 and 4) with respect to the levels of IGF-1 and IGFBP-3 (P < 0.01) 3 wk after the operation. HBOT or GH and combined therapy augmented on neomucosal formation. The use of combined therapy produced a synergistic effect on the histological, morphological and functional parameters.

Mesquite bean and cassava leaf in diets for Nile tilapia in growth

This work evaluated the inclusion of mesquite bean bran (Prosopis juliflora) and cassava leaf bran (Manihot esculenta) in diets for Nile tilapia (85.22 ± 3.13 g). Three hundred and thirty-six fish were distributed in 28 fiberglass tanks (120 L) in a 2 × 4 factorial scheme for two sources of oil and four levels of bran (0, 5, 10 and 20%) (n = 4). After 60 days, growth performance (feed intake, weight gain, apparent feed conversion and survival rate) and fish body composition were evaluated. Heights and density of villi were measured for morphometric analysis of the intestinal mucosa. Animal performance, body composition and villi density were not affected (p &gt; 0.05) by the source and level of inclusion of bran. There was a significant effect of the level of inclusion of bran on villi height, with a linear trend, indicating that the higher the inclusion levels of bran, the lower the height of the villi. The bran studied can be used in diets for Nile tilapia up to 20% without compromising growth performance and body composition change, but the presence of these by-products can result in a deleterious effect on fish villi.

Role of the mTOR complex 1 pathway in the in vivo maintenance of the intestinal mucosa by oral intake of amino acids

Oral intake of nutrients is often compromised in elderly, multimorbid patients, but parenteral nutrition causes intestinal atrophy and impairs intestinal function. To uncover the molecular mechanisms by which amino acids are involved in intestinal atrophy and recovery, we studied whether the rapamycin-sensitive mechanistic target of rapamycin (mTOR) complex 1 (mTORC1) pathway is involved in this process. C57BL/6N mice were fed a glucose solution alone, glucose solution with amino acids or normal chow diet for various lengths of time. Intestinal sections were prepared from these mice and the villus height and villus density were quantified. As a readout for the mTORC1 pathway, the phosphorylation of the ribosomal S6 protein (S6) was analyzed by immunostaining and immunoblotting. To confirm the role of the mTORC1 pathway, the inhibitory effect of a specific mTOR inhibitor, rapamycin, was examined. Inducing fasting in mice fed only glucose caused time-dependent intestinal mucosal atrophy, whereas supplementation with amino acids protected the intestinal mucosa from atrophy. Phosphorylation of S6 decreased in the intestinal mucosa of mice fed only glucose, whereas supplementation with amino acids increased S6 phosphorylation. Importantly, intraperitoneal injection of rapamycin attenuated the protective effect of amino acids on the intestinal mucosa in a pattern consistent with the decrease of S6 phosphorylation. These results indicate that the mTORC1 pathway plays a crucial role in the in vivo maintenance of the intestinal mucosa by the oral intake of amino acids.

Changes in pig small intestinal absorptive area during the first 14 days of life

The aim of this study was to evaluate the changes in small intestine absorptive area during the first 14 days of life in the pig. The duodenum and mid-jejunum were studied in a total of 16 piglets. Tissue samples were prepared for light microscopy (LM) and scanning electron microscopy (ScEM) at days 0, 3, 7 and 14 of life. The changes in villi density, height and width, crypt depth, mucosa thickness and amount of transversal furrows were used to appraise the surface of absorptive area. According to LM data, villus length and width, crypt depth and mucosa thickness increases from day 0 to day 3, and decreases from day 3 to day 14. ScEM study showed that the villus density reduced from day 0 to day 14 in duodenum, and from day 0 to day 3 in mid-jejunum. The surface of absorptive area was increased almost 3-fold in the duodenum from day 3 to day 7 and more than 2-fold in the jejunum in the same period.

Effects of dexamethasone on small bowel and kidney oxidative stress and histological alterations in bile duct-ligated rats

Oxidative stress plays an important role in the pathogenesis of toxic liver diseases and other hepatic alterations including obstruction of bile flow. It has been shown that the gastrointestinal tract and renal tissue is particularly affected during obstruction of bile flow. In this study, we aimed to evaluate the effects of dexamethasone on small bowel and kidney oxidative stress and histological alterations in bile duct-ligated (BDL) rats. A total of 40 male Sprague-Dawley rats weighing 200-240 g were used in this study. Group 1 (Sham-control, n = 10) rats underwent laparotomy and bile duct was dissected from the surrounding tissue. Group 2 (Dexa-control, n = 10) rats underwent laparotomy and bile duct was dissected from the surrounding tissue. The rats received daily dexamethasone. Group 3 (BDL/Untreated, n = 10) rats were subjected to bile duct ligation and no drug was applied. Group 4 (BDL/Dexa, n = 10) rats received daily dexamethasone by orogastric tube for 14 days after BDL. At the end of the 2-week period, superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), and malondialdehyde (MDA) were measured and biochemical and histological evaluation were processed. The mean serum bilirubin, liver enzymes, MDA level, and histopathological score significantly decreased and SOD, CAT, and GSH-Px values were significantly increased in group 4 when compared to group 3. Group 3 presented a significant increase in caecal count of E. coli and in aerobe/anaerobe ratio. In group 4, liver was moderately damaged. Ileal biopsies from group 4 demonstrated a significant increase in villus height, total mucosal thickness, and villus density when compared to group 3. Glomerular injury scores (GIS) and arterial injury scores (AIS) in group 3 rats were increased in the juxtamedullary region. In contrast to group 4, tubulo-interstitial lesions were diffuse in group 3 animals. Dexamethasone reduced small bowel and kidney oxidative stress and histological alterations in bile duct-ligated rats with increasing SOD, CAT, and GSH-Px and decreasing MDA levels in rats with obstructed bile duct.

Intestinal mucosa development in broiler chickens fed natural growth promoters

This study evaluated the use of probiotics and prebiotics on the histological and morphological indexes of the intestinal mucosa of broilers at 21 days of age. Thirty-six birds were randomly distributed in a 3 x 3 factorial arrangement, considering 3 probiotics and prebiotics sources in the diet. There were 9 treatments with 4 repetitions. Diet treatments were: 1 - Control (without growth promoters); 2 - Bacillus subtilis-based probiotic (Pro 1); 3 - Probiotic (Pool) based on Lactobacillus acidophilus and casei, Streptococcus lactis and faecium, Bifidobacterium bifidum and Aspergillus oryzae (Pro 2); 4 - Prebiotic based on Phosphorylated Mannanoligosaccharide (MOS) and Organic Acidifier (OA) (Pre 1); 5 - MOS-based prebiotic (Pre 2); 6 - Pro 1 + Pre 1; 7 - Pro 1 + Pre 2; 8 - Pro 2 + Pre 1; 9 - Pro 2 + Pre 2. Higher villus height (VH) (p<0.01) were seen in the duodenum of birds fed diets without prebiotics, whereas birds fed Bacillus subtilis-based probiotic and birds fed prebiotic based on MOS and OA showed higher VH (p<0.01) in jejunum and ileum. Greater crypt depths (CD) (p<0.01) were observed in the duodenum, jejunum and ileum of birds receiving B. subtilis, and in the duodenum and jejunum of birds fed diets without prebiotics. Significant interaction (p<0.01) between the evaluated factors was seen for both, VH and CD, in the three intestinal portions. Greater VH was obtained in duodenum, jejunum and ileum with the use of probiotics and prebiotics and greater CD with the use of probiotics, in relation to the control group. There was no difference in villus density (VD) between birds fed diets without additives or diets containing probiotics and prebiotics. Nevertheless, there was a significant interaction (p<0.05) between the evaluated factors for VD in the duodenum. Concluding, beneficial effects were seen in histological indexes of the intestinal mucosa with the use of probiotics and prebiotics at 21 days of age.

Objective evaluation of the efficacy of daily topical applications of cosmetics bases using the hairless mouse model of atopic dermatitis

Dry skin (xerosis) is a characteristic change associated with atopic dermatitis (AD) and has often been treated with topical petrolatum applications despite its unfavorable feel. Recently, various therapeutically effective skin-care products with better feel have been introduced. To elucidate the mechanisms underlying the clinical effectiveness of these newer treatments, we used our recently established hairless mouse model of AD. We produced AD-like skin lesions in hairless mice with repeated applications of 2,4,6-trinitro-1-chrolobenzene (TNCB) in acetone for 36 days as reported previously. Groups of five mice with AD-like skin were treated once daily with an emollient-type cream containing petrolatum, a moisturizer-type cream containing 10% glycerin, a solution of 0.01% dexamethasone in acetone, or were left untreated. Over the duration of these treatments, we conducted non-invasive measurements of skin surface condition with biophysical instruments and electron microscopic evaluation of the surface area size and density of rear surface villi of superficial corneocytes. We also obtained skin biopsy samples and blood samples at each time point for histopathological evaluation and to assess serum IgE levels, respectively. After cessation of topical TNCB applications, AD-like skin underwent spontaneous resolution with normalization of skin appearance. A similar reduction in skin fold thickness was observed in the cream-treated mice and in the untreated mouse group, whereas a significant decrease in skin thickness was observed in the dexamethasone-treated mice. Transepidermal water loss, a measure of stratum corneum barrier function, rapidly normalized in all groups, without any statistical differences noted among groups. In comparison with untreated skin, skin surface hydration markedly improved after repeated applications of the moisturizer-type cream, whereas it consistently remained low in dexamethasone-treated skin. The skin treated with emollient-type cream appeared similar to skin that received no treatment. Reduced corneocyte surface area size resulting from repeated applications of TNCB returned to control size with cream treatments, while the corneocyte surface area size became much larger following dexamethasone treatment. In addition, the density of villi on the rear surface of corneocytes decreased with application of the creams or dexamethasone. By contrast, no changes were observed in the number of leukocytes in the epidermis or in serum IgE levels among the different treatment groups. In all treatment groups, even after 32 days of treatment, reapplication of TNCB resulted in early-stage skin swelling, but only in the steroid-treated animals did this swelling show a remarkably prolonged time course. Our present results indicate that the efficacy of skin-care products containing no active ingredients in treating atopic xerosis can be objectively evaluated using the hairless mouse model of AD.

Effect of bombesin and neurotensin on gut barrier function in partially hepatectomized rats

To investigate the effect of regulatory peptides bombesin (BBS) and neurotensin (NT) on intestinal barrier function in partially hepatectomized rats. Ninety male Wistar rats were randomly divided into five groups: I (n=0): controls, II (n= 20): sham operated, III (n=20): partial hepatectomy 70% (PHx), IV (n=20): PHx+BBS (30 microg/kg/d), V (n=20): PHx+NT (300 microg/kg/d). Groups IV and V were treated for 8 days before PHx and 48 h post surgery. At the end of the experiment, on day 10, intestinal barrier function was assessed by measuring endotoxin concentrations in portal and aortic blood. Tissue sections of the terminal ileum were examined histologically and villus density, mucosal thickness, mitotic activity and apoptosis in crypts were assessed. In addition, ileal mucosa was analyzed for DNA and protein content and microbiological analysis was performed in cecal contents. To estimate intestinal oxidative stress, lipid peroxidation was determined on tissue homogenates from terminal ileum. BBS or NT administration significantly reduced portal and systemic endotoxemia observed 48 h after partial hepatectomy. In hepatectomized rats (group III), a trend towards induction of mucosal atrophy was observed, demonstrated by the reduction of villus density, mucosal thickness, protein content and significant reduction of DNA, while these alterations were reversed by regulatory peptides administration. This trophic effect of BBS and NT was accompanied by induction of mitoses above control levels and a significant reduction of apoptosis in intestinal crypts. Intestinal lipid peroxidation was found significantly lower in PHx group and regulatory peptides exerted an antioxidant action, further decreasing this parameter of oxidative stress. The bacterial population of E. coli and aerobic Gram (+) cocci was increased in cecal content of hepatectomized rats, while this parameter was not affected by the administration of BBS or NT. Gut regulatory peptides BBS and NT improve intestinal barrier function and reduce endotoxemia in experimental partial hepatectomy. This effect is, at least in part, mediated by their trophic, anti-apoptotic, mitogenic, and antioxidant effect on the intestinal epithelium. This observation might be of potential value in patients undergoing liver resection.

Effects of incremental starvation on gut mucosa.

Starvation induces gut mucosal atrophy, but the effects of progressive dietary restriction are not defined. The study's purpose was to determine the effects of incremental starvation on gut epithelial cell turnover. After food intake of mice was determined, they were divided into five groups: control (ad libitum fed), 75% normal intake, 50% intake, 25% intake, and fasted. Mice were killed after 48 hours, and the proximal small bowel were assessed for weight and protein content. Histologic specimens were examined for villus morphology, apoptosis, and proliferation. After 48 hr of diet restriction, bowel weight decreased in the 50% intake, 25% intake, and fasted groups. Villus density also decreased in the fasted group. Proliferation progressively decreased in the diet-restricted groups. Apoptosis increased in the fasted group, primarily in the villus tip. In conclusion, incremental starvation produces progressive small bowel atrophy. The mechanism involves both decreased gut epithelial cell proliferation and increased apoptosis.

Effects of intrinsic denervation on intestinal morphology in rats with short-bowel syndrome.

When benzalkonium chloride solution (BACs) is locally applied, to the serosal surface of the intestine, it causes intrinsic denervation (ID) of the myenteric plexus (MP), changes intestinal morphology, and slows intestinal passage by prolonging small-bowel transit time. These effects of ID suggest that chemically-induced bowel denervation may be useful in the treatment of short-bowel syndrome (SBS). How ID affects intestinal morphology in rats with SBS has not previously been investigated. A 75%-80% mid-small-bowel resection was performed in 20 rats with mean body weight 247 +/- 30 g. The proximal and distal 2 cm of the resected bowel were examined histologically. After intestinal continuity was maintained by end-to-end anastomosis, a 2-cm jejunal segment was marked with silk sutures to form the test segment. BACs 0.1% was applied to 10 of the 20 test segments according to the modified Fox method, resulting in MP destruction (G1). Saline solution was applied to the other 10 test segments to form the control group (G2). Three months later, the rats were killed and the jejunal, ileal, and test segments were evaluated morphologically. Results were expressed as mean +/- standard deviation. The Wilcoxon parametric test was performed to compare the groups during the operation and after death, while the Mann Whitney U-test was used to compare the data in G1 and G2. No intestinal obstruction was observed in either group. In G1, the body weight increased by 19.1% and the total small-intestinal lengthening was 62.2% (P < 0.05). In the test segment of G1, 75% of the ganglia in the MP were destroyed and villus height, crypt depth, intestinal muscle thickness, number of enterocytes, and villus density increased compared to G2. In the ileal segments of G1, there was an increase of 28.8% in intestinal diameter, 14% in muscle thickness, and 15% in villus density (P < 0.05). No change was observed in the untreated jejunal segments of G1 and G2. Thus, ID of the MP after segmental BACs application of the jejunal level: (1) does not cause intestinal obstruction after 3 months; (2) the increase in bowel diameter in the test and ileal segments increases the absorptive surface of the mucosa; (3) the morphologic changes in the test and ileal segments verify an increase in intestinal adaptation; and (4) BACs application in rats with SBS is an easy procedure with no morbidity or mortality, and can be used to increase intestinal adaptation in rats with SBS.

Loss of E2F4 Activity Leads to Abnormal Development of Multiple Cellular Lineages

We have generated mice deficient in E2F4 activity, the major form of E2F in many cell types. Analysis of newborn pups deficient in E2F4 revealed abnormalities in hematopoietic lineage development as well as defects in the development of the gut epithelium. Specifically, we observed a deficiency of various mature hematopoietic cell types together with an increased number of immature cells in several lineages. This was associated with an increased frequency of apoptotic cells. We also found a substantial reduction in the thickness of the gut epithelium that normally gives rise to crypts as well as a reduction in the density of villi. These observations suggest a critical role for E2F4 activity in controlling the maturation of cells in a number of tissues.

Differential sugar absorption as a marker for adaptation in short bowel syndrome

Purpose: There are no reliable monitoring methods for following up with patients with short bowel syndrome (SBS). This study examines the use of inert sugar markers (mannitol and lactulose) as indicators of the surface area increases occurring with adaptation. Methods: Juvenile male rats underwent either transection with intestinal reanastomosis or resection with removal of the proximal 90% of the small bowel, leaving 10 cm of terminal ileum (n = 8 in each group). Animals were studied in vivo, measuring absorption of mannitol and lactulose on day 7, 14, and 28 and killed with the representative histological samples taken on day 7, 14, and 28. Results: Resected animals showed significant increases in intestinal length (initial bowel length 10 cm, final length 17.8 ± 1.4 cm, while transected showed no significant changes (101 ± 2 cm): resection also increased intestinal circumference (initial circumference 0.5 cm ± 0.1 cm, final circumference 1.1 cm ± 0.2 cm in resected animals, while transected animals remained unchanged). Resected animals also showed significant increases in villus height (0.7 ± 0.06 mm initially, 0.9 ± 0.09 mm at day 28), and but a decrease in villus density (116 ± 20 villi/mm2 initially, 78 ± 20 villi/mm2 at day 28), again controls showed no changes. This resulted in a significant increase in intestinal surface area in resected animals over the study; surface area initially calculated at 640 ± 80 cm2 increasing to 1,440 ± 360 cm2, while controls showed no significant change in surface area. There was also an increase in mannitol absorption, which went from 1.8 ± 0.6% on day 7 to 2.56 ± 0.6% on day 28 in resected animals, while permeability actually decreased over time. (All data mean ± SD, with P <.05 by Student's t test). Mannitol absorption correlated well with intestinal surface area (R2 = 0.82). Conclusion: These results suggest that inert sugar markers, such as lactulose and mannitol, may be useful in following adaptation in patients who have short bowel syndrome. J Pediatr Surg 35:661-664. Copyright © 2000 by W.B. Saunders Company.

Partial intestinal obstruction induces substantial mucosal proliferation in the pig

Parenteral nutrition and improving supportive treatment have resulted in prolonged survival for patients with short bowel syndrome. However, definitive therapy for patients with short bowel syndrome must focus on increasing small intestinal mucosal mass. Intestinal lengthening procedures rely on intestinal dilation to accomplish this. The authors hypothesized that partial intestinal obstruction would result in consistent dilation of the intestine and would provide increased intestinal mass for use in intestinal lengthening. The authors developed a partially obstructing prosthetic valve to dilate the intestine before intestinal lengthening. This report describes the changes elicited by the valve. Twelve weanling pigs were divided randomly into two groups of six. One group had valve placement 240 cm distal to the ligament of Treitz; the other had sham surgery. The survival rate was 100% for both groups, and the mean weight gain was similar. Both groups were fed pig chow mush and were killed 5 weeks after surgery. Intestinal diameter was measured, and the small intestine was harvested, preserved, and sectioned for microscopic examination. The mean bowel diameter 15 cm proximal to the valve was 4.7 cm in the valved group and 3.3 cm in the sham group (42% increase). Total mucosal thickness, villus height, crypt depth, and villus density were significantly greater for the valved pigs in all sections (proximal and distal to the valve). Surface index and intestinal circumference were significantly greater in the valved pigs in all sections proximal to the valve, but there was no significant difference in these values for sections distal to the valve. There was no significant difference in villus cell density between the two groups at any location. Chronic partial obstruction of the small intestine results in consistent dilation of the intestine, with growth of all layers of the bowel, including the mucosa. This dilation and mucosal growth results in a true increase in surface area and is an ideal first step toward sequential lengthening.

Restitution of swallowing in the fetal sheep restores intestinal growth after midgestation esophageal obstruction.

We have shown that, in the fetal sheep, abolition of fluid ingestion early in gestation results in a profound gastrointestinal tract (GIT)-specific growth retardation and that these effects can be reversed if fetal swallowing is restored, even for relatively short periods (15 days). The fetal esophagus was ligated at 60-65 days of gestation in 11 fetal sheep (term is 145-148 days). At 136 days of gestation, body and tissue growth of six fetuses were compared to eight age-matched control fetuses. There were no effects on body growth, but the growth of the GIT was significantly retarded. The small intestine was the most severely affected region; villi were smaller in both proximal and distal regions, and villus density was increased and crypt density decreased. The growth-retarding effects are progressive such that they become more pronounced as the period of absence of swallowed input to the GIT is increased. Thus the effects observed in our study (ingestion abolished for approximately 80 days) are much more marked than those in our earlier short-term studies (40-50 days). Five of the fetuses with esophageal ligations underwent further surgery at approximately 120 days' gestation to correct the esophageal obstruction so as to allow the resumption of fluid ingestion. By 136 days, the values of most intestinal morphological parameters had begun to move toward control values.(ABSTRACT TRUNCATED AT 250 WORDS)

Small Intestinal Development in Growth‐Retarded Fetal Sheep

SummaryThe functional maturity of the gastrointestinal system is essential for the survival of the neonate. The effects of reducing placental size and the ensuing fetal growth retardation on the development of the small intestine (SI) of the sheep fetus were investigated. At 140 days of gestation (term is 147 days), fetal body weight, gastrointestinal weight (from the abomasum to the rectum, i.e., the gut), SI weight, and SI length in the growth‐retarded fetuses (n = 6) were significantly reduced (p &lt; 0.05) when compared with age‐ and breed‐matched control fetuses. The SI weight was disproportionately reduced as a fraction of the gut weight or SI length (p &lt; 0.01). The proximal SI showed marked reductions in the thickness of the wall, muscularis externa, mucosa, villus height, and crypt depth (p &lt; 0.003). Densities of villi and crypts were also reduced (p &lt; 0.02). The crypt‐to‐villus ratio was maintained. Glycogen was accumulated basally in the villus epithelial cells, and their nuclei were located apically. These characteristics are comparable to those of much younger fetuses. In the distal SI, interanimal variation was large; however, the mean thickness of the wall, the muscularis externa, the mucosa, and the villus height were all reduced (p &lt; 0.05). In this region, the density of villi and crypts, the pattern of glycogen accumulation, and the position of the nuclei did not markedly differ between growth‐retarded and control fetuses. Villus cell density was increased (p &lt; 0.01). Thus, fetal growth retardation due to placental insufficiency affects the proximal and distal SI with different degrees of severity, with thinning of the SI wall, a reduction of the surface area available for absorption, reduced epithelial regenerative capacity, and possibly a retardation of normal epithelial maturation.

Small intestinal development in growth-retarded fetal sheep.

The functional maturity of the gastrointestinal system is essential for the survival of the neonate. The effects of reducing placental size and the ensuing fetal growth retardation on the development of the small intestine (SI) of the sheep fetus were investigated. At 140 days of gestation (term is 147 days), fetal body weight, gastrointestinal weight (from the abomasum to the rectum, i.e., the gut), SI weight, and SI length in the growth-retarded fetuses (n = 6) were significantly reduced (p less than 0.05) when compared with age- and breed-matched control fetuses. The SI weight was disproportionately reduced as a fraction of the gut weight or SI length (p less than 0.01). The proximal SI showed marked reductions in the thickness of the wall, muscularis externa, mucosa, villus height, and crypt depth (p less than 0.003). Densities of villi and crypts were also reduced (p less than 0.02). The crypt-to-villus ratio was maintained. Glycogen was accumulated basally in the villus epithelial cells, and their nuclei were located apically. These characteristics are comparable to those of much younger fetuses. In the distal SI, interanimal variation was large; however, the mean thickness of the wall, the muscularis externa, the mucosa, and the villus height were all reduced (p less than 0.05). In this region, the density of villi and crypts, the pattern of glycogen accumulation, and the position of the nuclei did not markedly differ between growth-retarded and control fetuses. Villus cell density was increased (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

The role of gastrin in the development of the gastrointestinal tract in fetal sheep.

We have investigated the role of gastrin in the development of the gastrointestinal tract during the latter part of gestation in fetal sheep. We surgically removed the major source of gastrin, the gastric (abomasal) antrum, from five fetuses at 90 days of gestation. The remaining abomasum was anastomosed to the pylorus allowing unobstructed flow of luminal contents. Another five fetuses, subjected to sham-antrectomies at 90 days, served as controls. Further surgery was performed in all fetuses at 120 days for the placement of vascular catheters to permit measurement of plasma gastrin concentrations. The fetuses were infused with [3H]thymidine to study villus cell migration rates. At 135 days of gestation samples of gastric (abomasal) fundus, and proximal and distal small intestine, were processed for histology and morphometric analysis. The antrectomized fetuses had significantly lowered plasma gastrin concentrations (P less than 0.025) between 120 and 135 days. At 135 days, the mean body weight, crown-rump length, total gut weight and small intestinal weight and length were not significantly different between the two groups. Similarly, there were no significant differences between groups in the mean thicknesses of the gut wall, mucosa and muscularis externa, or in the mean villus height and crypt depth in the proximal or distal parts of the small intestine. Villus cell migration rate in the proximal and distal small intestine was not affected by antrectomy. No simple relationship could be demonstrated between any of these parameters and plasma gastrin concentration. In the antrectomized fetuses, the mean crypt density and crypt-to-villus ratio were significantly reduced in the proximal small intestine (P less than 0.05), while only the density of villi was reduced in the distal small intestine (P less than 0.05). In the antrectomized fetuses there were significant correlations between plasma gastrin and the fraction of fundic mucosa occupied by gland and pit (P less than 0.005), and between plasma gastrin concentration and villus density (P less than 0.01) and crypt-to-villus ratio (P less than 0.025) in the proximal small intestine. In the sham group these correlations were absent. We conclude that the removal of the gastric antrum in fetal sheep results in decreased plasma gastrin concentration, and that gastrin appears to have a regulatory or trophic role on the gut mucosa in these circumstances.(ABSTRACT TRUNCATED AT 400 WORDS)

Dietary fat selectively alters transport properties of rat jejunum.

The influence of dietary fatty acid composition on intestinal active and passive transport function, brush border membrane composition, and morphology was examined in rats. Animals fed a semisynthetic diet high in saturated fatty acids demonstrated enhanced in vitro jejunal uptake of decanoic, dodecanoic, palmitic, stearic, and linoleic acid, as well as cholesterol and chenodeoxycholic and taurochenodeoxycholic acid, as compared with uptake in animals fed a semisynthetic diet high in polyunsaturated fatty acids but equivalent in total content of fat and other nutrients, or as compared with Purina chow. Feeding the saturated fatty acid diet was also associated with reduced jejunal uptake of a range of concentrations of glucose, enhanced ileal uptake of leucine, unchanged uptake of galactose, and lower uptake of decanol. The semisynthetic diets did not alter brush border membrane protein, sucrase or alkaline phosphatase activities, cholesterol, or total phospholipids, although the percentage of jejunal amine phospholipids was higher than in rats fed chow. The morphologic differences between the jejunum and ileum were abolished in animals fed the high polyunsaturated fatty acid diet; in rats fed the high saturated fatty acid diet, there was reduced mean ileal villus height, width, thickness, surface area, cell size, and villus density, as well as reduced mucosal surface area. The changes in jejunal transport were not correlated with the alterations in morphology, unstirred layer resistance, food intake, or body weight gain. It is proposed that small changes in the percentage of total dietary lipids composed of essential and nonessential fatty acids (without concurrent alterations in dietary total fat, carbohydrate, or protein) influence active and passive intestinal transport processes in the rat.