长爪沙鼠肠道生长抑素和P 物质细胞密度的年龄变化

胃肠激素对调节小哺乳动物的消化功能具有重要作用。本文应用卵白素- 生物素- 过氧化物酶复合物(Avidin-biotin-peroxidase complex,ABC)免疫组织化学法,对冬季幼年、成年和老年长爪沙鼠肠道生长抑素(Somtostatin,SS)和P 物质(Substance P,SP)细胞进行了定位和比较。结果显示:不同年龄组两种内分泌细胞的形态学特征相似,呈圆形、椭圆形、梭形、锥形或不规则形。SS 细胞随年龄增加而分布范围缩小,主要分布于小肠和十二指肠,老年鼠的结肠和直肠无分布;盲肠段老年鼠高于幼年鼠和成年鼠,其余各段均无年龄差异。幼年鼠、成年鼠和老年鼠SP 细胞分别以结肠、盲肠和直肠密度为最高,成年鼠结肠和直肠无分布;肠道各段的密度均有年龄差异。这些结果表明,长爪沙鼠肠道SS 和SP 细胞的分布模式和发育特点有年龄差异,这可能与其生存环境的食物质量和两种内分泌细胞相互拮抗的消化生理功能有关。     

Functional Anatomy of the Alimentary Canal in the Fruit Bat,Eidolon helvum,and the Insect Bat,Tadarida nigeriae

The gastrointestinal anatomy of the frugivorous bat, Eidolon helvum was compared with that of the insectivorous bat, Tadarida nigeriae. Both show modifications related to differences in their food habits as well as other anatomical peculiarities. The gastroesophageal junction in Eidolon helvum possesses a sphincter-like protrusion. The posterior 10 mm of the esophagus in the same bat has well developed gastric glands, while the stomach is unexpectedly very rich in zymogenic and parietal cells. The intestine in this species is about 170 cm long; the posterior 30 cm of this is of colonic histology, though showing no external morphological difference from the small intestine. The anterior duodenum of Tadarida nigeriae has an external protuberance consisting of mucus secreting glands. The intestine of this bat has no colon, but a very short rectum of goblet cells is present.     

Light and electron microscopic studies on the absorptive cells of the intestine, caeca and rectum of the adult rainbow trout, Salmo gairdneri, Rich

The absorptive cells lining the mucosa of the intestine, caeca and rectum of farm-reared adult rainbow trout ( Salmo gairdneri Rich.) were studied by light and electron microscopy. Most of the intestinal absorptive cells showed morphological characteristics of lipid absorption. The cytoplasm of a few cells was closely packed with mitochondria. The caecal absorptive cells resembled those of the intestine but contained more apical dense bodies and more complex lamellar structures which, in conjunction with the intercellular spaces, appeared to play more active roles in lipid absorption. The rectal lumen was divided into peripheral and central parts by the complex mucosal folds. The surface of the peripheral part was mostly lined by vacuolated cells except for small patches of non–vacuolated (generative) cells between the bases of the folds. The central lumen was lined mainly by a second type of non-vacuolated cell. The vacuolated cells showed structural indications of a function of absorption of protein macromolecules.
There is morphological evidence to suggest that the pattern of absorption of lipids and proteins in the adult rainbow trout is similar to that demonstrated in stomachless teleosts and that both intraluminal and intracellular digestion of proteins co-exist in this teleost.     

Electron microscopic studies of the digestive tract and absorption from the gut lumen of a feather star,oligometra serripinna (Echinodermata)

Summary The gut of a crinoid echinoderm is described for the first time by transmission electron microscopy. The gut comprises a short esophagus, a relatively long intestine and a short rectum. From the luminal side to the coelomic side, the layers of the gut wall are an inner epithelium, an epineural plexus (much reduced or absent in the intestine and rectum), haemal fluid, smooth muscles mixed with a hyponeural plexus, and a visceral peritoneum. The inner epithelium of the esophagus consists of numerous flagellated enterocytes and some mucous cells containing abundant mucous granules. The luminal surface of the esophagus, but not that of the other gut regions, is covered by a conspicuous cuticle. The inner epithelium of the intestine consists of some exocrine cells, presumably exporting digestive enzymes to the gut lumen, and numerous vesicular enterocytes that are flagellated and contain a few apical mucous granules. The inner epithelium of the rectum is made up entirely of vesicular enterocytes most of which lack a flagellum. The uptake of macromolecules from the gut lumen was demonstrated by feeding the feather stars food mixed with ferritin. By 4 h after feeding, ferritin was identified in presumed secondary lysosomes within the enterocytes of the esophagus and within the vesicular enterocytes of the intestine and rectum. The functional implications of the new fine structural results are discussed.     

长爪沙鼠肠道5-羟色胺细胞密度的季节变化

为探讨季节性环境对长爪沙鼠肠道5-羟色胺(5-hydroxytryptamine,5-HT)细胞密度动态的影响,于2003
年11 月(冬季)和2004 年7 月(夏季),采用卵白素-生物素-过氧化物酶复合物(avidin-biotin-peroxidase complex,
ABC)免疫组织化学法,对其肠道5-HT 细胞进行了定位研究。结果显示:5-HT 细胞主要分布于肠上皮基
底部和肠腺上皮中,多呈圆形或椭圆形,少数呈长棒状、锥体形或不规则形,其形态学特征无季节性差异。冬
季在小肠密度最高,十二指肠、盲肠和直肠其次,结肠最低;夏季在小肠和十二指肠密度最高,其它各段密度
相似,这可能与其食物质量的季节性变化有关。除十二指肠和结肠外,冬季肠道各段的密度都高于夏季,这有
利于提高处理和消化食物的能力,是对冬季食物质量和摄食量增加的适应。5-HT 细胞的形态学特征和季节动态
说明,长爪沙鼠肠道在细胞水平上可对环境条件的变化产生反应,具有适应性调节的能力。     

Impacts of Dietary Pleurotus eryngii Polysaccharide on Nutrient Digestion,Metabolism, and Immune Response of the Small Intestine and Colon—An iTRAQ‐Based Proteomic Analysis

Pleurotus eryngii polysaccharides have been shown to exert significant biological activities to the host. However, few studies have been conducted on its effects on gastrointestinal tract (GIT) health alteration. In the present study, small intestinal and colonic proteome alterations generated by dietary supplementation with a novel homogeneous P. eryngii polysaccharide (PEP) in C57BL/6 mice, based on the isobaric tag for relative and absolute quantification (iTRAQ) proteomics, are investigated. Compared to the control group, PEP supplementation result in a total of 113 and 194 significant differential proteins (DPs) in the small intestine and colon, respectively. Interestingly, DPs in small intestine are mainly related to the transport and biosynthetic process, along with the digestion and absorption pathway of nutrients, whereas the colonic DPs are significantly found participating in numerous metabolic processes. Moreover, the alterations of some DPs in small intestine and colon are speculated to correlate with the colonic microbiota structure and are involved in the regulation of host immune response. Subsequently, some critical DPs of small intestine and colon are selected and validated by Western blotting. The current research facilitated the generation of potential insights into the health benefit activities and functional mechanisms of polysaccharides from P. eryngii.     

Functional morphology of digestion in the stomachless,piscivorous needlefishes Tylosurus gavialoides and Strongylura leiura ferox (Teleostei: Beloniformes)

Belonidae are unusual in that they are carnivorous but lack a stomach and have a straight, short gut. To develop a functional morphological model for this unusual system the gut contents and alimentary tract morphology of Tylosurus gavialoides and Strongylura leiura ferox were investigated. The posterior orientation of the majority of the pharyngeal teeth supports the swallowing of whole large prey, but not their mastication. Mucogenic cells are abundant in the mucosa lining, particularly the esophagus, and their secretions are likely to protect the gut lining from damage while lubricating passage of the prey. Esophagus, anterior intestine, posterior intestine, and rectum all have highly reticulate mucosae. The anterior three gut sections are distensible to accommodate the passage of prey. However, following ingestion large prey are passed to the highly distensible posterior intestine where they rest head first against the ileorectal valve. Alimentary pH ranges from neutral to weakly acidic. Fish prey is digested head first with the head being largely digested while the remainder of the body is still intact. The nondistensibility of the rectum and the small aperture provided by the ileorectal valve suggest the products of intestinal digestion are either small particulates or fluids that pass into rectum where they are absorbed. J. Morphol. 2009. © 2009 Wiley‐Liss, Inc.     

Gut ultrastructure of the appendicularian Oikopleura dioica (Tunicata)

Abstract. The appendicularians, planktonic tunicates, possess a specialized, external filtering system that captures food particles <1 μm in size. In this work the alimentary canal of Oikopleura dioica has been studied by serial sections of whole animals and ultrastructure. The gut includes a dorsal esophagus, a bilobed saccular stomach, and a curved intestine, divided into vertical, mid-, and distal intestine (or rectum). No multicellular glands or cellular proliferative centers were found. Three main cell types were recognized, ciliated microvillar cells, globular cells and gastric band cells, with specializations reflecting different physiological roles in the various regions. Ciliated microvillar cells, the most diffuse, are considered to be involved in food propulsion, fecal pellet formation, absorption, and nutrient storage. Pinocytotic features and vacuoles suggest that absorption of macromolecules and intracellular digestion occur in the globular cells of the stomach and rectum. The large gastric band cells of the left lobe have typical features of intense protein synthesis and probably produce enzymes for extracellular digestion. Diffuse interdigitations of many cells enormously increase the plasmalemma surface and may be involved in liquid/ion exchange. Despite the apparent structural simplicity of the gut epithelium, O. dioica efficiently processes food to fulfill the energy requirements of its exceptionally rapid life-cycle.     

Immunological differences in intestine and rectum of Atlantic cod (Gadus morhua L.)

The defence system of the distal gut (hindgut and rectum) of Atlantic cod, (Gadus morhua L.) was studied using (immuno)histochemical, electron microscopical and real-time quantitative PCR techniques. The uptake and transport of macromolecules in the intestinal epithelium was also investigated.In this study we observed that cod has many and large goblet cells in its intestinal epithelium and that IgM⁺ cells are present in the lamina propria and their number is considerably higher in the rectum than in the intestine. Myeloperoxidase staining revealed low numbers of granulocytes in and under the epithelium of the distal intestine, whereas high numbers were found clustered in the submucosa of the rectum. Electron microscopy not only confirmed these observations, but also revealed the presence of lymphoid cells and macrophages within the intestinal epithelium. Acid phosphatase staining demonstrated more positive macrophage-like cells in the rectum than in the distal intestine. Antigen uptake studies showed a diffused absorption of horse radish peroxidase (HRP) and LTB-GFP, whereas ferritin uptake could not be detected.Basal gene expression of cytokines (IL-1β, IL-8 and IL-10) and immune relevant molecules (hepcidin and BPI/LPB) were compared in both the intestine and rectum and revealed approximately 2–9 times higher expression in the rectum, of which IL-1β expression showed the most prominent difference.The present results clearly indicate that intestinal immunity is very prominent in the rectum of cod.     

Immunohistochemical study on the ontogenetic development of the regional distribution of peptide YY, pancreatic polypeptide, and glucagon-like peptide 1 endocrine cells in bovine gastrointestinal tract

The regional distribution and relative frequency of peptide YY (PYY)-, pancreatic polypeptide (PP)-, and glucagon-like peptide 1 (GLP-1)-immunoreactive (IR) cells were determined immunohistochemically in the gastrointestinal tract at seven ontogenetic stages in pre- and postnatal cattle. Different frequencies of PYY-, PP-, and GLP-1-IR cells were found in the intestines at all stages; they were not found in the esophagus and stomach. The frequencies varied depending on the intestinal segment and the developmental stage. The frequencies of PYY- and PP-IR cells were lower in the small intestine and increased from ileum to rectum, whereas GLP-1-IR cells were more numerous in duodenum and jejunum, decreased in ileum and cecum, and increased again in colon and rectum. The frequencies also varied according to pre- and postnatal stages. All three cell types were most numerous in fetus, and decreased in calf and adult groups, indicating that the frequencies of these three types of endocrine cells decrease with postnatal development. The results suggest that these changes vary depending on feeding habits and adaptation of growth, secretion, and motility of intestine at different ontogenetic stages of cattle.     

Distribution of enteric nerve cells that project to the coeliac ganglion of the guinea-pig

Summary The digestive tract of the guinea-pig, from the esophagus to the rectum, was examined in detail to determine the distribution and relative abundances of neurons in these organs that project to the coeliac ganglion and the routes by which their axons reach the ganglion. A retrogradely transported neuronal marker, Fast Blue, was injected into the coeliac ganglion. The esophagus, stomach, gallbladder, pancreas, duodenum, small intestine, caecum, proximal colon, distal colon and rectum were analysed for labelled neurons. Retrogradely labelled neurons were found only in the myenteric plexus of these organs, and in the pancreas. No labelled neurons were found in the gallbladder or the fundus of the stomach, or in the submucous plexus of any region. A small number of labelled neurons was found in the gastric antrum. An increasing density of labelled neurons was found along the duodenum. Similarly, an increasing density of labelled neurons was found from proximal to distal along the jejuno-ileum. However, the greates densities of labelled neurons were in the large intestine. many labelled neurons were found in the caecum, including a high density underneath its taeniae. An increasing density of labelled neurons was found along the length of the proximal colon, and labelled neurons were found in the distal colon and rectum. In total, more labelled cell bodies occurred in the large intestine than in the small intestine. The routes taken by the axons of viscerofugal neurons were ascertained by lesioning the nerve bundles which accompany vessels supplying regions of the digestive tract. Viscerofugal neurons of the caecum project to the coeliac ganglion via the ileocaeco-colic nerves; neurons in the proximal colon project to the ganglion via the right colic nerves, and neurons in the distal colon project to the ganglion via the mid colic and intermesenteric nerves. Neurons in the rectum project to the coeliac ganglion via the intermesenteric nerves. These nerves (except for the intermesenterics) all join nerve bundles from the small intestine that follow the superior mesenteric artery. All viscerofugal neurons of the caecum were calbindin-immunoreactive (calb-IR) and 94% were immunoreactive for vasoactive intestinal peptide (VIP-IR). In the proximal colon, 49% of labelled neurons were calb-IR and 85% were VIP-IR. In the distal colon, 80% of labelled neurons were calb-IR and 71% were VIP-IR.     

Morphology of the gastrointestinal tract in primates: Comparisons with other mammals in relation to diet

Three categories of dietary adaptation are recognized—faunivory, frugivory, and folivory—according to the distinctive structural and biochemical features of animal matter, fruit, and leaves respectively, and the predominance of only one in the diets of most species. Mammals subsisting mainly on animal matter have a simple stomach and colon and a long small intestine, whereas folivorous species have a complex stomach and/or an enlarged caecum and colon; mammals eating mostly fruit have an intermediate morphology, according to the nature of the fruit and their tendency to supplement this diet with either animal matter or leaves. The frugivorous group are mostly primates: 50 of the 78 mammalian species, and 117 of the 180 individuals included in this analysis are primates. Coefficients of gut differentiation, the ratio of stomach and large intestine to small intestine (by area, weight, and volume), are low in faunivores and high in folivores; the continuous spread of coefficients reflects the different degrees of adaptation to these two dietary extremes. Interspecific comparisons are developed by allowing for allometric factors. In faunivores, in which fermentation is minimal, the volume of stomach and large intestine is related to actual body size, whereas these chambers are more voluminous in larger frugivores and mid-gut fermenting folivores; fore-gut fermenters show a marked decrease in capacity with increasing body size. Surface areas for absorption are related to metabolic body size, directly so in frugivores; area for absorption is relatively less in larger faunivores and more in larger folivores, especially those with large stomachs. Indices of gut specialization are derived from these regressions by nonlinear transformation, with references to the main functional features of capacity for fermentation and surface area for absorption. These are directly comparable with the dietary index, derived from quantitative feeding data displayed on a three-dimensional graph, with all species within a crescentic path from 100% faunivory through 557ndash;80% frugivory to 100% folivory, perhaps illustrating, at least for primates, the evolutionary path from primitive insectivorous forms through three major ecological grades.     

Distribution and morphological features of nitrergic neurons in the porcine large intestine

The distribution of nitric oxide synthase (NOS), an enzyme involved in the synthesis of the presumed non-adrenergic noncholinergic inhibitory neurotransmitter nitric oxide (NO), was demonstrated in the enteric nervous system of the porcine caecum, colon and rectum. Techniques used were NOS-immunocytochemistry and nicotinamide adenine dinucleotide phosphate diaphorase (NADPHd)-histochemistry. Throughout the entire large intestine, NOS-immunoreactive (IR) and NADPHd-positive neurons were abundant in the myenteric and outer submucous plexus. In the inner submucous plexus, only a small number of positive neurons were found in the caecum and colon, while a moderate number was observed in the rectum. The nitrergic neurons in the porcine enteric nerve plexuses were of a range of sizes and shapes, with a small proportion showing immunostaining for vasoactive intestinal polypeptide. Varicose and non-varicose NOS-IR and NADPHd-positive nerve fibres were present in the ganglia and connecting strands of all three plexuses. Nerve fibres were also numerous in the circular muscle layer, scarce in the longitudinal muscle coat and negligible in the mucosal region. The abundance of NOS/NADPHd in the intrinsic innervation of the caecum, colon and rectum of the pig implicates NO as an important neuronal messenger in these regions of the gastrointestinal tract.     

Morphological changes in the middle intestine of the rainbow trout,Salmo gairdneri,induced by a hyperosmotic environment

Summary The structural modifications in the middle intestine of the trout, Salmo gairdneri, induced by transfer to seawater have been studied. During the first two days in seawater, significant distensions of the intercellular spaces are observed between the apical tight junctions and the basement membrane. These dilations are more frequent in the apical part of the intestinal folds. At the basal part of the cell, numerous lamellar processes open in the intercellular spaces. They are closely associated with elongated mitochondria, and are often mixed with small clear vesicles. After seven days in seawater, intercellular spaces are less expanded. Numerous mitochondria are observed in the apical part of the cell, and numerous myelinic bodies with dense granules lie near the nucleus. After one month in seawater, the epithelium resembles that of the freshwater controls; mitochondria are more numerous and other organelles are well developed. The most important modifications of the ultrastructure of the intestine mucosa occur during the first two days in seawater, in correlation with important physiological changes following the abrupt increase of environmental salinity.     

Role of bats in the ecology of Paracoccidioides brasiliensis: the survival of Paracoccidioides brasiliensis in the intestinal tract of frugivorous bat, Artibeus lituratus

The fruit-eating bat, Artibeus lituratus, was fed known quantities of viable yeast cells and mycelial particles of Paracoccidioides brasiliensis in an attempt to assess the role of this animal in the distribution of this agent in nature. Results of mycosal cultures of the stomach, upper intestine, lower intestine and rectum clearly showed that the fungal cells were unable to survive more than 8 hours in the digestive tract of the bat. The mycelial particles were more susceptible than the yeast and were killed before passing to the rectum. The fungus died rapidly in the voided fecal material. These findings indicate the improbability of isolating P. brasiliensis from the digestive tract of wild captured bats and show that A. lituratus probably plays no role in the distribution of this fungus in nature.     

Feeding of the Bat,Sturnira lilium,on Fruits of Solanum riparium Influences Dispersal of this Pioneer Tree in Forests of Northwestern Argentina

The influence of fruit ingestion by the bat, Sturnira lilium, on germination of the seeds of the tree Solanum riparium was studied in a secondary rain forest in northwestern Argentina. Bat frequencies in disturbed areas were analyzed by mist net captures. Germination rates were determined for seeds collected from trees and bat feces. S. lilium was the most abundant fruit bat in the study area. Fruit digestion and the passage of seeds through the intestine did not significantly affect germination in S. riparium. In this case the fruit bats, therefore, probably provide only seed dispersal.     

Immunohistochemical analysis of ZnT1, 4, 5, 6, and 7 in the mouse gastrointestinal tract.

Expression of five zinc transporters (ZnT1, 4, 5, 6, and 7) of the Slc30 family in the mouse gastrointestinal tract was studied by immunohistochemical analysis. Results demonstrated unique expression patterns, levels, and cellular localization among ZnT proteins in the mouse gastrointestinal tract with some overlapping. ZnT1 was abundantly expressed in the epithelium of the esophagus, duodenum of the small intestine, and cecum of the large intestine. ZnT4 was predominantly detected in the large intestine. ZnT5 was mainly expressed in the parietal cell of the stomach and in the absorptive epithelium of the duodenum and jejunum. ZnT6 was predominantly detected in the chief cell of the stomach, columnar epithelial cells of the jejunum, cecum, colon, and rectum. Lastly, ZnT7 was observed in all epithelia of the mouse gastrointestinal tract with the highest expression in the small intestine. Expression of ZnT proteins in the absorptive epithelial cell of the gastrointestinal tract suggests that ZnT proteins may play important roles in zinc absorption and endogenous zinc secretion.     

Repeated Examinations, Using the Laparotomy Sampling Technique, of the Gastro-intestinal Microflora of Baboons Fed a Natural or a Synthetic Diet

S ummary . Semi-quantitative studies on serial gastro-intestinal aspirates taken at laparotomy showed an increase in both numbers and types of organisms on passing down the baboon intestine from stomach to colon. In baboons fed a natural diet of fresh fruit and vegetables, the stomach, duodenum, and jejenum were sparsely populated, the flora consisting mainly of yeasts and lactobacilli, together with small numbers of faecal streptococci, micrococci and staphylococci. The mid-ileum was more heavily populated, yeasts, lactobacilli and faecal streptococci being present in most samples, while lactose-fermenting enterobacteria were isolated from half the aspirates, and in some, small numbers of micrococci, staphylococci and Clostridium welchii were present. The caecum and colon aspirates were heavily populated with all the organisms mentioned above. Differences between the intestinal flora of baboons fed the natural diet and baboons fed a synthetic diet were similar to the difference noted previously (Uphill, 1973) for the faecal flora. The suitability of laparotomy technique as a means of examining the flora of the various regions of the baboon gut is discussed.     

Distribution of neurokinin-2 receptors in the guinea-pig gastrointestinal tract

The distribution of neurokinin-2 (NK2) tachykinin receptors was investigated by immunohistochemistry in the guinea-pig oesophagus, stomach, small and large intestine. Receptor immunoreactivity occurred at the surfaces of smooth muscle cells throughout the digestive tract. Nerve fibre varicosities in enteric ganglia were also immunoreactive. In myenteric ganglia, these varicosities were most numerous in the ileum, frequent, but less dense, in the proximal colon and caecum, rare in the distal colon, extremely infrequent in the rectum and duodenum, and absent from the stomach and oesophagus. Reactive varicosities were rare in the submucous ganglia. Reactive nerve fibres in the mucosa were only found in the caecum and proximal colon. Strong NK2 receptor immunoreactivity was also found on the surfaces of enterocytes at the bases of mucosal glands in the proximal colon. Receptors were not detectable on the surfaces of nerve cells or on non-terminal axons. Reactivity did not occur on nerve fibres innervating the muscle. Denervation studies showed that the immunoreactive varicosities in the myenteric plexus of the ileum were the terminals of descending interneurons. Immunoreactivity for nitric oxide synthase was colocalised with NK2 receptor (NK-R) immunoreactivity in about 70% of the myenteric varicosities in the small intestine. Bombesin immunoreactivity occurred in about 30% of NK2-R immunoreactive varicosities in the small intestine. Received: 10 April 1996 / Accepted: 13 May 1996     

Trypanosoma cruzi: effects of azadirachtin and ecdysone on the dynamic development in Rhodnius prolixus larvae

The effects of azadirachtin and ecdysone on the Trypanosoma cruzi population in the Rhodnius prolixus gut were investigated. T. cruzi were rarely found in the gut compartments of azadirachtin-treated larvae. High parasite numbers were observed in the stomach of the control and ecdysone groups until 10 days after treatment and in the small intestine and rectum until 25 days after treatment. High percentages of round forms developed in the stomachs of all groups, whereas azadirachtin blocked the development of protozoan intermediate forms. This effect was counteracted by ecdysone therapy. In the small intestine and rectum, epimastigotes predominated for all groups, but more of their intermediates developed in the control and ecdysone groups. Azadirachtin supported the development of round forms and their intermediates into trypomastigotes. In the rectum, trypomastigotes did not develop in the azadirachtin group and developed much later after ecdysone therapy. The parallel between the effects of azadirachtin and ecdysone on the host and parasite development is discussed on the basis of the present results because ecdysone appears to act directly or indirectly in determining the synchronic development of T. cruzi forms from round to epimastigotes, but not metacyclic trypomastigotes, in the invertebrate vector.