Cellular kinetics of villous epithelial cells and m cells in rabbit small intestine

The cellular kinetics of villous columnar epithelial cells and M cells in the rabbit small intestine were determined by the use of 5-bromo-2'-deoxyuridine (BrdU) as a tracer. To identify M cells, vimentin antibody was used. The BrdU-labeled nuclei of columnar epithelial cells reached the base of intestinal villi in all portions at 1 day after BrdU administration. Thereafter, BrdU-labeled cells migrated toward the villous tip, but they did not move at a uniform speed. The epithelial cells which existed in intestinal villi on circular folds moved faster than those on mucosa other than circular folds. At 7 days after BrdU administration, the leading edge of BrdU-labeled epithelial cells already disappeared from the villous tip in all portions of the small intestine. In the ileal Peyer's patch, the BrdU-labeled nuclei of microvillous epithelial cells and vimentin-positive M cells appeared near the intestinal crypt orifice at 1 day after BrdU administration, and then migrated toward the luminal surface of the follicle-associated epithelium (FAE). As they moved toward the upper portion of FAE, the number of BrdU-labeled M cells on the side of the dome decreased simultaneously. The leading edge of BrdU-labeled epithelial cells disappeared from the top of the FAE within 7 days. These results suggest that M cells may differentiate from the undifferentiated cells in intestinal crypts within 1 day and disappear from the top of the FAE after the change of their form from M cells into microvillous epithelial cells.     

Distribution of the pores of epithelial basement membrane in the rat small intestine

The distribution and diameter of the pores of epithelial basement membrane in the intestinal villi and the lymph nodules of ileal Peyer's patches were investigated in the rat small intestine by scanning electron microscopy after the removal of the overlying epithelial cells with OsO(4) maceration. In the duodenum, jejunum and ileum, the pores were mainly distributed at the upper three fourths of the villi, but were scarce around the top of the villi. The diameter of some of the pores in the upper three fourths of the villi was larger than that of those in the lower portion. The protrusion of lymphocytes and the cytoplasmic processes of macrophages were also seen at the orifices of the pores. In ileal Peyer's patches, in contrast, pores were densely distributed in the lower one third of the follicle-associated epithelium (FAE) where M cells were mainly seen. Furthermore, these pores were larger than those found in the upper two thirds. Lymphocytes or cytoplasmic processes of macrophages were frequently seen in the lower one third of FAE. These results suggest that the pores at the basement membrane correspond to the passage of the immunocompetent cells which are in contact with M cells or villous columnar epithelial cells and that the abundance of pores is a sign of aggressive interaction between the particular epithelial cells and the immunocompetent cells at the upper three fourths of intestinal villi and the lower one third of FAE in the rat small intestine.     

The pathogenesis of enteric colibacillosis in neonatal unsuckled calves.

The development of pathological lesions in the small intestine of neonatal calves is described. Seven newborn calves were challenged orally with a known enteropathogenic strain of E coli 0101k?(A) and killed at varying times after inoculation. Adhesion of bacteria to the mucosa of the small intestine was observed in all calves. A few organisms were seen in the distal small intestine at three hours after inoculation and thereafter adhesion progressed anteriorly along the intestine in calves killed from six to 36 hours. In these calves pathological changes occurred between six and 12 hours after inoculation. Villi were stunted and thickened and the epithelial surface was irregular. A further calf, anaesthetised from five-and-a-half to 10 hours after inoculation and repeatedly sampled from the distal small intestine, developed similar lesions abruptly at nine hours after inoculation. Villus and crypt lengths in the challenged calves were compared with those in three normal uninoculated control calves.     

Scanning and transmission electron microscopy of attaching effacing Escherichia coli in weanling rabbits

A strain of an enteropathogenic Escherichia coli, originally isolated from diarrheic weaned rabbits, produced diarrhea in five-week-old New Zealand white rabbits. Sequential examination of the intestines by scanning and transmission electron microscopy revealed that the strain attaches first to the Peyer's patch dome epithelium and later to the enterocytes of distal small intestine, cecum, and colon. Colonized cells became rounded and detached. The colibacilli were intimately associated with the apical cell membrane. Both absorptive and goblet cells were affected. The strain caused effacement of the microvillous border of colonized epithelial cells. Colibacilli were regularly seen in the partially evacuated cavities of goblet cells, but not in absorptive epithelial cells.     

Morphologic Effects of Experimental Distention of Equine Small Intestine

The morphologic effects of induced intraluminal hydrostatic pressures (IHPs) of 0, 9, and 18 cm H₂O were evaluated in 33 isolated equine jejunal segments. Fifteen segments were distended with Tyrode's solution for 1 hour and nine segments for 4 hours. Tyrode's solution was added as needed to maintain the prescribed pressures. Nine other segments were left undisturbed for 4 hours after the initial distention period. On decompression of the intestinal segments, progressive peristaltic contractions resumed in all segments. Evaluation of intestinal sections by light microscopy and transmission electron microscopy showed edema of the villi and submucosa and separation of the epithelial cells adjacent to the basement membrane in all segments. The epithelial cell necrosis found in ischemic intestine was not seen. This study indicates that the necrosis found at the villous tips in distended sections of small intestine remote from the site of obstruction cannot be reproduced by IHP increases of 4 hours duration.     

A scanning and transmission electron microscopic study of rotavirus-induced intestinal lesions in neonatal gnotobiotic dogs

Neonatal gnotobiotic dogs orally inoculated with canine rotavirus had ultrastructural changes limited to the jejunal and ileal regions of the small intestine. Early scanning electron microscopic findings consisted of swollen villus epithelial cells, denuded foci on intestinal villi, and slight to moderate villus atrophy. Later changes were slight villus atrophy with no denuded intestinal villi. Transmission electron microscopic changes in villus epithelial cells from 12 to 48 hours post-inoculation included: rotavirus particles associated with intracytoplasmic vacuoles near the terminal web and apical tubules; viral particles in dilated cisternae of rough endoplasmic reticulum; and moderate numbers of necrotic cells having no microvilli, swollen mitochondria, membrane-bound lipid-like material in the cytoplasm, clumped chromatin around the periphery of the nucleus, and disruption of the cytoplasmic membrane. In jejunum and ileum at 72 to 154 hours post-inoculation, there were fewer necrotic villus epithelial cells and fewer virus particles. In addition, the ultrastructural morphology of the majority of the villus epithelial cells was similar to crypt epithelium. These studies showed that rotavirus infected the villus epithelial cells with subsequent propagation of the rotavirus and destruction of villus epithelial cells.     

Immunohistochemical study on the delayed progression of epithelial apoptosis in follicle-associated epithelium of rat Peyer's patch

It is well known that some caspases in apoptosis is involved in determinant of terminal differentiation and maturation of various cells. Our previous study ultrastructurally clarified the differentiation into M cells from immature microvillous epithelial cells and the redifferentiation from M cells to microvillous epithelial cells in the follicle-associated epithelium (FAE) of rat Peyer's patch. In this study, the difference of epithelial apoptosis between the FAE of Peyer's patch and intestinal villi was immunohistochemically investigated in rat jejunoileum. As a result, cleaved caspase-3 was limited to several epithelial cells at the tip of FAE, whereas almost all of the epithelial cells were cleaved caspase-3 positive in intestinal villi. Cleaved caspase-9 was detected only in a few exfoliating or exfoliated epithelial cells of both FAE and intestinal villi. Nuclear DNA-fragmentation was detected only in several epithelial cells of the tip of FAE, while it was expressed from the middle regions in the intestinal villi. The DNase I expression of the epithelial cytoplasm was much weaker in FAE than in intestinal villi. Bcl-x expression was restricted in the apical cytoplasms of epithelial cells in the FAE, whereas it was restricted in whole cytoplasms in villous epithelial cells. These findings suggest that the progression of the apoptotic process in the epithelial cells of FAE is later than in the intestinal villi, so that the possibility of epithelial differentiation might be remained in the FAE, unlike in the intestinal villi.     

Lesions of gnotobiotic calves experimentally infected with a calicivirus-like (Newbury) agent

Fourteen gnotobiotic calves were killed 0.5 to ten days after infection with Newbury agent SRV-1 and the changes in small intestinal structure and function were assessed, qualitatively and quantitatively, by light microscopy, scanning and transmission electron microscopy, enzymology and xylose absorption. The first enterocytes detected as infected by immunoperoxidase were those on the sides of villi at the base. Subsequently exfoliation of degenerate enterocytes resulted in stunted villi; mucosal beta-galactosidase activity fell and there was xylose malabsorption. Small intestinal damage, first detected at 12 hours after infection but almost repaired by ten days, was restricted to the anterior half of the small intestine. In the distal small intestine, where no virus-induced damage occurred, villi lengthened--possibly due to increased mitosis of crypt cells stimulated by enteroglucagon release.     

Apoptosis of villous epithelial cells and follicle-associated epithelial cells in chicken cecum

The process of the disappearance of epithelial cells was examined in chicken cecal villi and follicle-associated epithelium (FAE). The apoptotic epithelial cells with intense DNA-fragmentation and their exfoliation were found in the villous tips. The epithelial cells with weak DNA-fragmentation were seen in the upper portion of the villi and their sparse exfoliations were also found there. Numerous epithelial cells in the intestinal lumen expressed the apoptotic features. A row of apoptotic epithelial cells with DNA-fragmentation was also found in the apical FAE, whereas no M cells exhibited any apoptotic signs. In all cecal regions, CD3+, CD8+, and TCR2+ lymphocytes were predominant in the epithelium at the upper portion of the villi and the FAE. CD4+ lymphocytes were mainly seen in the lamina propria. TCR1+ lymphocytes were not abundant in comparison with TCR2+ lymphocytes in the epithelium. TCR3+ T lymphocytes were rarely detected. These results suggest that the chicken cecal epithelial cells exfoliated into the lumen after the induction of the apoptosis, and that the induction may be involved with CD3+, CD8+, and TCR2+ lymphocytes. No death in M cells suggests that M cells may transform into microvillous epithelial cells.     

Intestinal lesions in specific-pathogen-free lambs associated with a cryptosporidium from calves with diarrhea

Small and large intestines of seven specific pathogen-free lambs infected with cryptosporidia from calves with diarrhea were examined by scanning and transmission electron microscopy and by light microscopy. The small intestine was infected in all the lambs, and the cecum and colon in three. Small intestinal alterations were severe villous atrophy and dilatation of the crypts of Lieberkühn. Epithelial cross-bridging between contiguous villi caused much villous fusion. Epithelial cells constituting the bridges were connected by desmosomal junctions, and were continuous with the epithelial coverings of the associated villi. The lamina propria was heavily infiltrated with neutrophil leukocytes. Infected crypts in cecum and colon were dilated and devoid of mucus-secreting cells, while the ridges between crypts were hypertrophied, and the lamina propria was infiltrated by neutrophils. Cell vegetations with adherent bacteria were present in the surface intestinal epithelium of two lambs infected for 11 and 14 days, respectively. No adherent bacteria were seen in any site in lambs killed up to six days post-inoculation.     

Gnotobiotic piglets experimentally infected with neonatal calf diarrhoea reovirus-like agent (Rotavirus).

Gnotobiotic piglets were infected with a strain of rotavirus that had been isolated from a calf and passaged four times in piglets. The resulting disease was studied by light and electron microscopy at 21, 44 and 68 h after inoculation. In the small intestine infection caused desquamation of the epithelial cells of the villi resulting in severe stunting. There was severe damage to microvilli and accumulation of lipid within the cytoplasm. Virus particles were seen in epithelial cells covering the stunted villi. Infection also caused desquamation of the superficial epithelial cells of the stomach mucosa and of the epithelial cells of the bronchi, bronchioles, and alveoli of the lungs.     

Über die frühfetale Entwicklung der Dünndarm-Mukosa des Rindes (Bos primigenius taurus).

The development of the bovine small intestine was examined in 24 embryos and fetuses by light microscopic, scanning and transmission electron microscopic methods. Special reference was paid to the genesis of the epithelium and particularly of the villi intestinales. The primitive intestine consists of one layer of epithelial cells surrounded by mesenchym and tunica serosa. The fetal intestine (up to the 24th week of gestation) shows all the morphologic structures of the adult. In small intestine the development of cryptae and villi intestinales starts before the 7th week of gestation and progresses with a proximo-distal gradient. Epithelial proliferation that gives rise to primary epithelial villi makes epithelium become temporarily stratified. Finger-like secondary villi develop by proliferation of the mesenchym. In addition to this process mucosal folds occur in duodenum giving rise to villi by segmentation. At the same time the differentiation of epithelium starts. The fetal small intestine, like many other fetal tissues displays masses of glycogen.     

Histochemical distribution of enzymes in the small intestine of young milk-fed calves

The histochemical distribution of selected enzymes were examined in the small intestine of 5 about 3-week-old normal calves fed on whole cow’s milk. Alkaline phosphatase and β-D-galactosidase (= lactase) in the epithelial brush border, and non-specific esterase in the cytoplasm showed a strong reaction in the villi of the anterior small intestine and a marked decrease in the posterior regions. Aminopeptidase in the brush border of the villi showed a reverse distribution, with the strongest reaction in the posterior small intestine. Adenosine-triphosphate-splitting enzyme in the epithelial brush border, acid phosphatase and succinate dehydrogenase in the cytoplasm of the epithelial cells gave a relatively uniform reaction in the villi throughout the small intestine. A fluoride-resistant acid phosphatase was demonstrated in the brush border of the villi in the anterior small intestine. The distribution of enzymes demonstrated in this study was generally compatible with the known absorptive functions of the various parts of the small intestine.     

Differences in lectin-binding properties between the common mucosal epithelium and follicle-associated epithelium in the rabbit small intestine

Differences in sugar distribution between the villous epithelium and follicle-associated epithelium (FAE) were compared using lectins in the rabbit small intestine. In every portion, villous columnar epithelial cells primarily exhibited a positive reaction to the GalNAc, GlcNAc, galactose, and oligosaccharide. In the ileal Peyer's patch (PP), whereas microvillous epithelial cells exhibited positive reactions, M cells tended to be negative. The villous epithelial reaction to the fucose group was negative, but M cells and microvillous epithelial cells showed a positive to the fucose. No epithelium had a positive reaction to the mannose and glucose. The variety of lectin-binding properties of villous epithelial cells and M cells may reflect specificity for the recognizing luminal substances such as antigenic molecules and bacterial elements.     

Scanning electron, light, and immunofluorescent microscopy of intestine of gnotobiotic calf infected with calf diarrheal coronavirus.

Intestinal lesions in 2 gnotobiotic calves given (oral inoculation) calf diarrheal coronavirus were studied by scanning electron, light, and immunofluorescent microscopy. The calves were euthanatized at 34 and 73 hours after the onset of diarrhea. Lesions in the small intestine were similar to those reported in animals affected with transmissible gastroenteritis of swine. Small intestinal villi were shortened, some adjacent villi were fused, and villous epithelium was composed of low cuboidal to squamous cells. In the ansa spiralis coli, there were atrophy of the colonic ridges and marked differences in length and spacing of the microvilli on individual epithelial cells.     

Pathological changes in the small intestine of neonatal calves naturally infected with reo-like virus (rotavirus).

Nine calves, of which six had been challenged with an enteropathogenic strain of Escherichia coli, were found to be naturally infected with rotavirus. Rotavirus was recovered from the faeces of six calves and rotavirus antigen was detected in the intestinal mucosa of all calves. Stunting and fusion of villi were seen principally in the proximal and middle small intestine, where rotavirus antigen was detected by immunofluorescence. Typical lesions of enteric colibacillosis were found in the distal ileum of the challenged calves, associated with adhesion of the challenge strain of E coli to the mucosa. All samples were removed from the intestine under general anaesthesia and denudation of villi was not observed. However, following exsanguination and resampling at the same site in the small intestine of one calf, denudation was a constant feature.     

实验性流行性腹泻仔猪小肠粘膜上皮细胞及肠系膜淋巴结的超微结构

给8头生后3d的哺乳仔猪经口感染猪流行性腹泻病毒(PEDV)“吉”毒株,于感染后18、30、45和96h各扑杀2头,以透射电镜和扫描电镜观察了小肠粘膜上皮细胞及肠系膜淋巴结的超微结构。结果表明,小肠上皮细胞的病变因感染时间不同而有明显差异。上皮细胞的脱落和残留上皮细胞超微结构的破坏,以感染后30h最严重,病毒在这些上皮细胞内的增殖最显著。感染后45h,见有大量新生上皮细胞修补损伤的肠绒毛。感染后96h,小肠绒毛短缩、粗大乃至发生融合。实验仔猪肠系膜淋巴结内巨噬细胞和淋巴细胞的超微结构均遭到破坏,在巨噬细胞内见有PED冠状病毒粒子。     

Fatal cryptosporidiosis in quail

Young quails kept in wire-floored cages experienced high mortality, beginning at age 5 days, from diarrhea that was unresponsive to antibiotic therapy. At necropsy, the small intestine had clear fluid content and the cecum was distended by brown foamy fluid. Histopathologic findings in the small intestine were shortened villi with detached enterocytes at the tip. Cryptosporidium sp. (confirmed by electron microscopy) were numerous in the microvillous border. Neither bacterial nor viral pathogens were detected. No infection was established in day-old chickens gavaged with feces and intestinal contents from infected quails. Thorough cleansing of the cages followed by application of commercial bleach prevented recurrence.     

Mycotoxicosis caused by aerosolized T-2 toxin administered to female mice

Thymus, spleen, adrenal glands, and small intestine of female mice exposed to aerosolized T-2 mycotoxin were examined at postexposure hours (PEH) 0.25, 1, 2, 4, 6, 9, 12, and 24. Lymphocyte necrosis was observed at PEH 1 in the thymus, spleen, and lamina propria and Peyer patches of the small intestine. Necrosis of small intestinal crypt epithelial cells was observed at PEH 2, and necrosis of parenchymal cells and increased number of neutrophils were seen in sinusoids of the adrenal cortex at PEH 4. These results indicated that the earliest microscopic evidence of T-2 mycotoxicosis after aerosol exposure was necrosis of lymphocytes in the thymus, spleen, and lamina propria and Peyer patches of the small intestine.     

几种酶分离山羊小肠上皮细胞方法的比较

用不同酶消化分离山羊小肠上皮细胞,从而找到最佳的分离方法,为进一步研究IEC提供合适的细胞模型.本研究分别用胶原酶Ⅰ、嗜热菌蛋白酶、胶原酶Ⅺ/中性蛋白酶Ⅰ消化分离刚出生未进奶的山羊小肠上皮细胞,通过观察IEC生长状态、形态特征、抗原鉴定比较哪种分离效果最佳.结果表明,联合用胶原酶Ⅺ/中性蛋白酶Ⅰ 1h可分离出大量健全绒毛隐窝单位,进一步培养获得的小肠粘膜上皮(IEC),上皮细胞膜抗原均呈阳性,用胶原酶Ⅰ和嗜热菌蛋白酶分离得到的大部分是成纤维细胞.选用用胶原酶Ⅺ/中性蛋白酶Ⅰ作为分离IEC的消化酶,可获得较纯的IEC.