Pathomorphology of the Intestinal Mucosa in Diarrheic Calves

The intestinal mucosa was examined in twelve 2–5-week-old calves with a spontaneous intestinal disorder, 8 with diarrhea and 4 convalescents. The calves were fed a defined milk replacer. Light microscopy including morphometry, showed villous atrophy and crypt elongation. Villous epithelial cells had decreased height, and epithelial cells of the posterior small intestine contained an increased amount of fat droplets. Accumulation of neutrophils in crypts was frequent. Scanning electron microscopy revealed blunt villi with increased numbers of necrotic cells in the extrusion zone at the tips of the villi. The convalescents had generally milder changes, particularly in the anterior small intestine. The probable etiological factors included a rotavirus and chlamydial infection, and it is concluded that these agents together with other possible noxious influences were responsible for the increased necrobiosis of apical senescent villous epithelial cells, resulting in villous atrophy and crypt hyperplasia.     

A morphologic analysis of denuding 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.     

Some morphological and histochemical studies on the intestinal tract of the Brazilian sloth (Bradypus tridactylus)

The intestinal of the 3-toed sloth, Bradypus tridactylus, was studied macroscopically, with light microscope and with histochemical methods for mucosubstances. Macroscopically, the inner surface of the duodenum shows longitudinal and circular folds. There is no caecum, nor appendix. The large intestine consists of a short colon and a large rectal pouch, which has a thick wall. The mucosa of the small intestine has long leaf-shaped villi covered with columnar epithelium having a well developed striated border, and the goblet cells are scattered among the columnar cells. An association between neutral and acidic mucosubstances was detected in the goblet cells. The duodenal (Brunner's) glands are confined exclusively in the lamina propria of the duodenum. No Paneth cells were observed in the crypt lining. Argyrophil and argentaffin cells were found in the entire length of the intestine. The large intestine does not possess villi, but many goblet cells were observed in its mucosa.     

An Enzyme Histochemical Investigation of the Intestinal Mucosa in Diarrheic Calves

Selected enzymes were examined in the small intestine of twelve 2–5 week-old calves, 8 with diarrhea and 4 convalescents. The diarrheic calves showed a reduction of enzyme reactions mainly in the duodenum and middle small intestine, and the crypt reactions appeared most severely affected. In the duodenum, villous alkaline phosphatase, adenosine triphosphate-(ATP)-splitting enzyme, and β-D-galactosidase were reduced in 3 calves; the reaction in the corresponding crypts was decreased in 6 calves for the ATP-splitting enzyme and in 4 calves for the β-D-galactosidase. Six calves showed decrease of villous brush border acid phosphatase, and 3 of villous non-specific esterase. In the middle jejunum, villous ATP-splitting enzyme was reduced in 3 calves, while 5 showed decrease of the corresponding crypt reaction. Convalescents had no enzyme reduction in the duodenum, whereas 1 showed marked reduction of the ATP-splitting enzyme and aminopeptidase in the middle and posterior jejunum. The decreased enzyme reactions in the present material may be caused by immaturity of epithelial cells associated with regenerative crypt hyperplasia and/or microbial destruction of enzymes.     

The distribution of polypeptide YY (PYY)- and pancreatic polypeptide (PP)-immunoreactive cells in the domestic fowl

Summary The distribution of the polypeptide which has an N-terminal tyrosine and a C-terminal tyrosine (PYY)- and pancreatic polypeptide (PP)-immunoreactive cells were investigated in the gut of the domestic fowl. PYY-immunoreactive cells were observed in the duodenum and jejunum. PP-immunoreactive cells were seen in the duodenum, jejunum, ileum and colon. Both PYY- and PP-immunoreactive cells were extended from the basal lamina to the gut lumen i.e. of open type. PYY-immunoreactive cells occurred mainly in the basal and middle portion of the villi. On the other hand, PP-immunoreactive cells were located mostly in the crepts. The occurrence of PYY-immunoreactive cells in the upper part of the small intestine is rather similar to that of amphibians and reptiles, than to that of mammals, where PYY-immunoreactive cells are located in the distal part of the small intestine and in the large intestine.Preliminary results were given in abstract form in the 4th International Symposium on Gastrointestinal Hormones, held in Stockholm, June 20–23, 1982     

Stereological studies on the small intestinal epithelium of the rat

Summary Quantitative macroscopic, light-microscopic and electron-microscopic studies were performed on the small intestine of fasted and non-fasted adult, male Sprague-Dawley rats. In non-fasted rats the small intestine was longer than in fasted rats. Due to the presence of villi the surface area in the duodenum and the jejunum was enlarged about six times. The microvilli on the villous crests caused a surface enlargement by 13 times in the duodenum (value corrected for overestimation due to section thickness), and 19 times in the jejunum of the fasted rats. At the base of the villi these values were about 50% lower. It was calculated that, in the fasted rats, the total enlargement of the luminal surface area — due to villi and microvilli — was 63 times in the duodenum and 81 times in the jejunum (corrected for section thickness).Differences between the villous crest epithelium and the villous base epithelium were also found with regard to the mean cell height, and the volume densities of the absorptive cell nuclei, the mitochondria, and the paracellular channels.Supported by grants from the Swedish Medical Research Council (Project No. 12X-2298), from the Swedish Group-Insurance Co. Förenade Liv, from Tore Nilson's Fund for Medical Research and from the Medical Faculty, University of Umeå     

Cellular Proliferation of Intestinal Epithelia in the Rat Two Months after Partial Resection of the Ileum

Sprague-Dawley rats subjected 2 months previously to partial resection (10 per cent) of the small intestine and their controls were injected with tritiated thymidine and sacrificed at 2 and 23 hours. Segments of the duodenum, jejunum, and ileum were autoradiographed, and the migration of the labelled cells during the period between 2 and 23 hours was measured with an eyepiece micrometer. The cells had migrated 35, 42, and 34 per cent of the total distance from the crypts to the tips of the villi in the control segments of duodenum, ileum, and jejunum respectively, and 43, 90, and 82 per cent, respectively, in similar segments from resected animals. The rate of migration in the portion of the intestine remaining after resection was approximately three times the normal rate in the ileum, twice the normal rate in the jejunum, and showed an increase of one-third in the duodenum. These results demonstrate that the rate of cell renewal is considerably greater in the remaining portion of the intestine of resected animals than in normal intestine. The increased rate of migration after resection, together with the increase in the height of the villi, resulted in an increase in the rate of cell renewal amounting to 141 per cent in the ileum, 114 per cent in the jejunum, and 23 per cent in the duodenum when compared with control segments.     

The effects of insulin on glucose and fluid transport in the isolated small intestine of normal rats

Chronically administered insulin returns enhanced maximal glucose transport capacity induced by diabetes to its normal state. In this study, the direct and acute effects of insulin on glucose transport in different parts of isolated small intestine were investigated. Mucosal Fluid Transport (MFT), Mucosal Glucose Transport (MGT) and Serosal Glucose Transport (SGT) were measured in the presence and absence of insulin in averted sacs, prepared from female Wistar rats. This study shows that the presence of insulin in vitro (40 and 80 microU/mL) can reduce MGT and SGT in different segments of the small intestine (duodenum, jejunum and ileum) after 30 min whereas it had no effect on MFT. Mucosal glucose transfer rates in the duodenum, jejunum and ileum of the controls were 6.07+/-0.4, 6.34+/-0.62 and 6.43+/-0.47 mg/g tissue respectively which were significantly reduced to 3.82+/-0.93, 3.60+/-0.50 and 1.17+/-0.45 in the presence of 80 microU/mL of insulin. Serosal glucose transfer too was decreased significantly from 0.3+/-0.05, 0.57+/-0.07 and 0.43+/-.07 in the duodenum, jejunum and ileum to 0.16+/-0.03, 0.16+/-0.04 and .07+/-.02 respectively. Mucosal fluid transfer was not affected by insulin. Insulin was as effective whether it was added on the mucosal or the serosal side. The results of this study show that insulin can directly affect glucose transport in the small intestine; its physiological role must be examined. Direct effect of insulin deficiency on glucose absorption in diabetic patients may play a role in the pathophysiology of the disease.     

Lactic acid is absorbed from the small intestine of sheep

A series of experiments was conducted in vivo on anaesthetized sheep to explore the hypothesis that lactic acid is absorbed from the small intestine of sheep. Test solutions varying in lactic acid concentration, pH, osmolarity, and with fixed physiological concentrations of volatile fatty acids (VFAs), K+, Na+, NH4 +, Cl-, and PO4 (-3), were separately introduced into clean, surgically sealed pouches. Studies were undertaken in 27 sheep, each with three pouches in the middle of the duodenum, jejunum, and ileum. Samples were taken at 15-minute intervals for 60 minutes to determine the absorption rates. The experimental results showed that L- and D-lactic acid were absorbed from the pouches of the duodenum, jejunum, and ileum throughout the 60 minutes. In the test solutions with pH 5.3, 420mOsmol/kg, and 12.5mM lactic acid that are in vivo conditions of light lactic acidosis, the mean absorption rates of D-lactic acid and L-lactic acid pooled from three pouches were similar, 0.07micro mol/cm2/min and 0.06micro mol/cm2/min, respectively, based on absorptive surface area. The mean absorption rates of DL-lactic acid from the duodenum, jejunum, and ileum pouches were almost the same, 0.14, 0.14, and 0.11micro mol/cm2/min, respectively. The absorption of lactic acid varied depending on lactic acid concentration, and there was a curvilinear relationship between lactic acid concentration and its absorption rate. A decrease in pH and osmotic pressure resulted in significant, corresponding increases in the absorption of lactic acid (P<0.0001 and P<0.05, respectively).     

Characterization and histochemical localization of the rat intestinal Na(+)-D-glucose cotransporter by monoclonal antibodies

The localization of the Na(+)-D-glucose cotransporter in rat small intestine was investigated with four monoclonal antibodies which were raised against porcine renal brush-border membrane proteins. The antibodies alter high affinity phlorizin binding or Na+ gradient-dependent D-glucose uptake in kidney and intestine. In both organs, the antibodies react with polypeptides with apparent molecular weights of 75,000 and 47,000. In pig kidney, these polypeptides were identified as components of the Na(+)-D-glucose cotransporter (Koepsell, H., K. Korn, A. Raszeja-Specht, S. Bernotat-Danielowski, D. Ollig, J. Biol. Chem. 263, 18419-18429 (1988)). The electron microscopic localization of antibody binding was investigated by immunogold labeling of ultrathin plastic sections. In villi and crypts of duodenum, jejunum and ileum the antibodies bound specifically to brush-border membranes of enterocytes and did not react with the basolateral membranes. The density of antigenic sites in brush-border membranes was highest in jejunum, intermediate in ileum and lowest in duodenum. On the tip, the middle and the basis of the villi the density of antigenic sites was similar. The data demonstrate homologous Na(+)-D-glucose cotransporters in kidney and intestine. They suggest that during maturation of the enterocytes when the total area of brush-border membrane increases, the concentration of the Na(+)-D-glucose cotransporter in the brush-border membrane remains constant. However, we found that different segments of small intestine not only contain different surface areas of the transporter-containing brush-border membrane per intestinal length but also different densities of the transporter within the brush-border membrane.     

An Electron Microscopic Study of the Intestinal Villus : II. The Pathway of Fat Absorption

The intestinal pathway for absorbed fat was traced in thin sections of intestinal villi from rats fed corn oil by stomach tube after a fast of 24 to 40 hours. For electron microscopy the tissues were fixed in chilled buffered osmium tetroxide and embedded in methacrylate. For light microscopy, other specimens from the same animals were fixed in formal-calcium, mordanted in K₂Cr₂O₇, and embedded in gelatin. Frozen sections were stained with Sudan black B or Sudan IV. About 20 minutes after feeding, small fat droplets (65 mµ maximal diameter) appear in the striated border between microvilli. At the same time fat particles are seen within pinocytotic vesicles in the immediately subjacent terminal web. In later specimens the fat droplets are generally larger (50 to 240 mµ) and lie deeper in the apical cytoplasm. All intracellular fat droplets are loosely enveloped in a thin membrane, the outer surface of which is sometimes studded with the fine particulate component of the cytoplasm. This envelope, apparently derived from the cell surface by pinocytosis, has at this stage evidently become a part of the endoplasmic reticulum. Just above the nucleus numerous fat droplets lie clustered within the dilated cisternae of the Golgi complex. As absorption progresses fat droplets appear in the intercellular spaces of the epithelium, in the interstitial connective tissue spaces of the lamina propria, and in the lumen of the lacteals. All of these extracellular fat droplets are devoid of a membranous envelope. The picture of fat absorption as reconstructed from these studies involves a stream of fat droplets filtering through the striated border, entering the epithelial cell by pinocytosis at the bases of the intermicrovillous spaces, and coursing through the endoplasmic reticulum to be discharged at the sides of the epithelial cell into extracellular spaces. From the epithelial spaces, the droplets move into the lamina propria and thence into the lymph. If the lumen of the endoplasmic reticulum is considered as continuous with the extracellular phase, then the entire pathway of fat absorption may be regarded as extracellular. However, it is impossible to evaluate from the electron microscopic evidence thus far available the quantitative importance of particulate fat absorption by the mechanism described.     

Ultrasonic observation on distribution of subcutaneous fat in Japanese young adults with reference to sexual difference

Utilizing an ultrasonic device (B-mode, 7.5MHz), the thickness of subcutaneous fat was measured at 54 different points in the bodies of 59 males (aged 20-25) and 66 females (aged 20-23). The results were as follows: 1. The females had significantly thicker subcutaneous fat than those of the males at every point measured. 2. The thick subcutaneous fats were observed at the abdomen, buttocks, and the anterior and medial parts of the thigh in the males, and at the breast, buttocks, abdomen, the posterior, medial, and anterior parts of the thigh, and the anterior, medial, and posterior parts of the upperarm in the females, respectively. 3. The subcutaneous fat of both sexes was more likely to be thicker in body parts closer to the trunk than the extremities. 4. The correlation coefficient between the percent body fat and the mean thickness of subcutaneous fat obtained from data was 0.91 for the males and 0.83 for the females.     

Localization of acyl-coenzyme A: cholesterol acyltransferase in villus and crypt cells of chick intestine

Endogenous cholesterol esterification by acyl-CoA:cholesterol acyltransferase (EC 2.3.1.26) was studied in isolated enterocytes obtained from chick duodenal, jejunal, and ileal villi and crypts, using [14C]oleoyl-CoA as substrate. The maximal specific activity in each cell fraction was found in chick jejunum, followed by duodenum and ileum. Jejunal upper and mid villi showed higher specific activities than lower villi and crypts. Epithelial cells isolated from chick intestine also incorporated oleoyl-CoA into different lipids using the endogenous substrates. Upper and mid villus cells showed the maximal incorporation of oleoyl-CoA into triglycerides in duodenum and jejunum. Levels of oleoyl-CoA incorporation into phospholipids were higher than those found in the synthesis of triglycerides or cholesterol esters, whatever may be the cell fraction considered. Upper villus cells also showed the highest specific activity in the incorporation of oleoyl-CoA into phospholipids. The acyl-CoA hydrolase specific activity was practically similar in all the cell fractions obtained from chick duodenum, jejunum, and ileum.     

The anatomicohistological characteristics of the formation of the mucosa of the human small intestine in the prenatal period of ontogeny]

The time, when the first villi appear, is defined. Quantitative composition, percent content, height of the villi of the mucous membrane in all parts of the small intestine during various periods of the intrauterine development are presented. In 17-week-old embryos at the level of the duodenum the first villi are noted and their formation in the middle part of the intestinal tube is revealed. By the 8th-9th weeks of development they appear at the level of the caudal part of the intestine. This demonstrates asynchronism of their formation in the cranio-caudal direction. The periods of their intensive growth in height in the first part of the intestine correspond to 8-10, 12-16, 24 weeks of the fetus age, in the second part--to 8-10, 18-20 weeks, in the third--to 10-12, 16-18, 26-28 weeks. These periods alternate with an abatement in growth intensity, which is connected with an increasing width of the villi themselves, with amount of newly formed villi and with changes of the intestinal tube diameter. The form of the villi is rather variable.     

Histological characteristics of the intestinal mucosa of the rat during the first year of life

In spite of the widespread use of rats in gastrointestinal research, there is a lack of information on the qualitative and quantitative histological characteristics. Therefore, a study was performed in 69 male Wistar rats with ages ranging from one day to one year old. The features studied included: height and number of villi in the duodenum, jejunum and ileum, and depth and number of crypts in the duodenum, jejunum, ileum, colon and rectum. Morphometric observations were expressed in a mathematical logarithmic curve that showed a normal, pattern of intestinal growth for each intestinal level. The number of villi in the small intestine decreased from 1 to 35 days of age, whereas the other intestinal parameters all increased during the same period. After 35 days the rates of increase or decrease were lower. The quantification of these intestinal changes provides a new complementary pattern as a reference for research as indicators of normality or malfunction in the rat intestine.     

Histochemical studies on iron absorption in Ophiocephalus punctatus and Heteropneustes fossilis.

Iron absorption in both the teleost fishes Ophiocephalus punctatus and Heteropneustes fossilis, initially starts after 2h of feeding the iron diet. However, at this stage, there is no absorption of iron in the posterior intestine of both the fishes. Absorption initially starts along the brush border of enterocytes of the villi. Later, it gets accumulated in the supranuclear region of the epithelial cells and then through these cells, it is transported into the cores of the villi. The absorbed amount ultimately reaches along the bases of the villi. Through the blood capillaries, which are situated in the submucosa, absorbed iron is passed on to the blood stream. Although, the entire intestine of both the fishes is able to absorb iron but the regional variations have been noted. In contrast to the posterior intestine, the anterior and middle intestine of both the fishes show better iron absorption. The pyloric caeca of Ophiocephalus have comparatively less affinity for iron absorption. However, the intestine of Heteropneustes shows more affinity for iron absorption than the intestine of Ophiocephalus.     

青海沙蜥消化道组织结构及嗜银细胞研究

为揭示青海沙蜥消化系统的组织结构,探索其高海拔适应的组织学基础,应用解剖学与石蜡切片、H.E染色和Grimelius银染法对青海沙蜥消化道组织结构和嗜银细胞进行研究。结果显示：青海沙蜥的消化道管壁结构分为4层,从内到外依次是粘膜层、粘膜下层、肌层和浆膜。消化道各段的长度和壁厚均存在显著差异,其中小肠最长,胃幽门部的管壁最厚。粘膜皱襞和绒毛的分布也存在差异,空肠部位的小肠绒毛数量最多,其次是十二指肠和回肠。嗜银细胞形状多样,广泛分布在消化道各段的黏膜上皮基部和黏膜上皮之间。胃体是嗜银细胞分布密度最高的部位,其次是贲门,回肠最低。与栖息在低海拔的有鳞类相比,青海沙蜥为适应高海拔环境,小肠的相对长度变长,胃体部嗜银细胞增多。     

Eimeria acervulina and E. tenella:effect on methionine absorption by the avian intestine.

Absorption of l-methionine in the duodenum of intestine of chicks infected with Eimeria acervulina was markedly less than in uninoculated controls or birds infected with E. tenella. Absorption of methionine in the jejunal area of E. acervulina-infected birds was reduced although not as drastically as in the duodenum. There was no difference in the rate of methionine absorption by the ileum. The kinetics of methionine absorption showed that V_max (maximum velocity) in the duodenum and jejunum of E. acervulina-infected birds was reduced when compared with the V_max found in uninoculated controls or E. tenella-infected birds. There was no difference in the K_t (transport constant) regardless of the infection or the region of the intestine examined. No major consistent effect of decreased pH on the rate of methionine absorption could be shown.The broadly spatulate villi seen, using the scanning electron microscope, in control and E. tenella infected duodenum were absent in E. acervulina-infected duodenum. Instead, the villi were reduced in height and noticeably thickened. This reduction in villar height suggests that a portion of the reduction in methionine absorption was related to the change in surface area and loss of transport loci due to damage of the mucosal surface.     

Histochemical features of the Muscovy duck small intestine during development

We demonstrated for the first time the distribution and morphology of argyrophil and of goblet cells in the mucosa of the small intestine of the Muscovy duck during development using the Grimelius silver staining and alcian blue/periodic acid-Schiff (AB/PAS) staining technique. The argyrophil cells distribution was variable over the length of the small intestine from embryonic day 24 (24E) to post-hatching day 13 (13d). In the villi most argyrophil cells belonged to the open-type, while in the crypts they belonged to the closed-type. In the duodenum the density of argyrophil cells was highest at hatching, while in the jejunum and in the ileum the highest density value was at hatching and 13d. AB/PAS-positive goblet cells appeared on the villi and crypts of the duodenum and jejunum at 30E, and in the ileum at hatching. The density of AB/PAS-positive cells was the highest in the three segments at hatching. The AB-positive cells, compared with the PAS-positive cells, predominated in villi and crypts of the three segments, moreover the rate of AB-positive cells to PAS-positive cells significantly decreased from 30E to 9d. An increase in argyrophil and goblet cells number during the later incubation and at hatching, could indicate the small intestine in that period is being prepared to face a new diet.