Nervous regulation of abomasum motor activity in sheep

Pharmacological studies of abomasum motor activity were carried out in 3 sheep with chronic fistulae in the rumen and the fundus and pyloric part of the abomasum. The contractions of these parts of the stomach were recorded by the balloon method. The obtained results showed that in the abomasum stimulation of alpha-adrenergic receptors raises the degree of motor activity while stimulation of beta-adrenergic receptors inhibits it. It has been shown also that the sympathetic system has a greater influence through the beta-adrenergic receptors on the motor activity of the pyloric part than on that of the fundus of the abomasum. The analysis of the records obtained after bilateral vagotomy demonstrated that the automatism of the pyloric part was greater than that of the fundus of the abomasum.     

Gizzard formation and the role of Bapx1

The anterior-posterior gut pattern is formed from three broad domains: fore-, mid-, and hindgut that have distinct functional, morphological, and molecular boundaries. The stomach demarcates the posterior boundary of the foregut. Avian stomachs are composed of two chambers: the anterior chamber (proventriculus) and the thick muscular posterior chamber (gizzard). Expression of candidate pattern formation control factors are restricted in the chick stomach regions such that Bmp4 and Wnt5a are not expressed in the gizzard. We previously implicated Bmp4 as controlling growth and differentiation of the gut musculature. Bmp4 is not expressed in the developing gizzard but is expressed in the rest of the gut including the adjacent proventriculus and midgut. Bapx1 (Nkx3.2) is expressed in the gizzard musculature but not in the proventriculus or midgut. We show ectopic expression of Bapx1 in the proventriculus results in a gizzard-like morphology and inhibits the normal proventricular expression of Bmp4 and Wnt5a. Overexpression of a reverse-function Bapx1 construct can result in a small stomach and ectopic extension of Bmp4 and Wnt5a expression into the gizzard. We suggest the role of Bapx1 is to regulate the expression of Bmp4 and Wnt5a to pattern the avian stomach.     

Functional morphology of the digestive tract epithelium in Phoronis vancouverensis (Pixell): an ultrastructural and histochemical study

The ultrastructure of the gut regions of the marine filter-feeder Phoronis vancouverensis was correlated with enzyme activity as revealed histochemically. The oesophagus, proventriculus, and stomach epithlia showed intense esterase and acid and alkaline phosphatase activity. The staining reaction was confined primarily to small globules in the apical cytoplasm of the epithlial cells. Electron micrographs of the same regions showed a high incidence of zymogenlike granules, with a corresponding abundance of ribosomes and of rough endoplasmic reticulum. Also, the proventricular and to a lesser extent the stomach epithelia were found to contain a large number of lipid bodies. This was confirmed with positive Sudan IV staining for fats. The intestinal region of the gut was found devoid of esterase and phosphatase activity. The epithelial surface in this region was found elaborated into microvilli. The entire gut is ci iated. A new paired-cilium apparatus is described in this phylum. From these findings Phoronis vancouverensis is concluded to be suitably adapted to its continuous filter-feeding existence, with the anterior gut epithelia synthesizing hydrolytic enzymes for release into the lumina of the proventriculus and stomach. Subsequently, in the hindgut the products of initial extra-cellular digestion are absorbed via the microvilli and treated intracellularly within the intestinal epithelium. The proventriculus is further thought to function in lipid absorption and storage. The presence of chromaffin-like granules observed in some proventricular and intestinal epithelial cells suggests that digestion in this phylum may in part be under neurosecretory control.     

Microbial diversity in the rumen,reticulum, omasum,and abomasum of yak on a rapid fattening regime in an agro-pastoral transition zone

The ruminant digestive system harbors a complex gut microbiome, which is poorly understood in the case of the four stomach compartments of yak. High-throughput sequencing and quantitative PCR were used to analyse microbial communities in the rumen, reticulum, omasum, and abomasum of six domesticated yak. The diversity of prokaryotes was higher in reticulum and omasum than in rumen and abomasum. Bacteroidetes predominated in the four stomach compartments, with abundance gradually decreasing in the trend rumen > reticulum > omasum > abomasum. Microorganism composition was different among the four compartments, all of which contained high levels of bacteria, methanogens, protozoa and anaerobic fungi. Some prokaryotic genera were associated with volatile fatty acids and pH. This study provides the first insights into the microorganism composition of four stomach compartments in yak, and may provide a foundation for future studies in this area.     

An immunohistochemical study of somatostatin in the stomach and the small intestine of the African ostrich (Struthio camelus)

The aim of the present study was to clarify the distribution and relative frequencies of somatostatin (SST)-producing cells in the stomach and the small intestine of the ostrich by using immunohistochemistry. The results indicated that somatostatin-immunoreactive (SST-IR) cells were distributed in mucosal layers of the proventriculus, duodenum, jejunum and ileum. However, no immunoreactivity was observed in the gizzard. SST-IR cells were found at the lower part of glandular lobule in the proventriculus, which were oval and round generally. SST-IR cells were present in the mucous membrane of entire small intestine of the ostrich. SST-IR cells had round and spherical shapes (closed-type cells), or spindle and pyriform shapes (open-type cells) in the small intestine. SST-positive cells were localized preferentially in the proventriculus of the 60-day-old ostrich. These results indicated that SST might be involved in functional and developmental regulation of gastrointestinal tract of the ostrich.     

Comparative studies on the gastric glycopeptide in eleven animal species.

1. Glycopeptides in the stomachs of eleven mammalian species, including human, rabbit, horse, cow, pig, goat, sheep, dog, cat, guinea pig and rat were assayed by determining the carbohydrate content of materials which remained after proteolysis. 2. The glycopeptide content was higher in the mucosa than in the muscular layer including serosa, especially in the porcine stomach and the fourth stomachs of the ruminants than in the stomachs of any other animals. 3. The glycopeptide, which was stained with both alcian blue and PAS, was absent or sparingly present in the mucosae of the human, rabbit, horse stomachs and in the mucosae of the first to third stomachs of the cow, goat and sheep, whereas in the mucosae of the pig, dog, cat, guinea pig and rat stomachs and in the mucosae of the fourth stomachs of the cow, goat and sheep, it was found in noticeable extents.     

The Effect of Plant Tissue and Vaccine Formulation on the Oral Immunogenicity of a Model Plant-Made Antigen in Sheep

Antigen-specific antibody responses against a model antigen (the B subunit of the heat labile toxin of enterotoxigenic Escherichia coli, LTB) were studied in sheep following oral immunisation with plant-made and delivered vaccines. Delivery from a root-based vehicle resulted in antigen-specific immune responses in mucosal secretions of the abomasum and small intestine and mesenteric lymph nodes. Immune responses from the corresponding leaf-based vaccine were more robust and included stimulation of antigen-specific antibodies in mucosal secretions of the abomasum. These findings suggest that oral delivery of a plant bioencapsulated antigen can survive passage through the rumen to elicit mucosal and systemic immune responses in sheep. Moreover, the plant tissue used as the vaccine delivery vehicle affects the magnitude of these responses.     

Histological and ultrastructural study of the digestive tract of rice field eel, Monopterus albus

The histological characteristics of the digestive tract and the ultrastructure of mucosal cells of the stomach and intestine of rice field eel, Monopterus albus, are described to provide a basis for future studies on its digestive physiology. The digestive tract of the rice field eel is a long and coiled tube composed of four layers: mucosa, lamina propria‐submucosa, muscularis and serosa. The pharynx and oesophagus mucosa is lined with a stratified epithelium. The stomach includes the cardiac and pyloric portions and the fundus. Many gastric pits are formed by invaginations of the mucosal layer and tubular gastric glands formed by the columnar cells in the fundus. The intestine is separated from the stomach by a loop valve and divided into a proximal portion and a distal portion. The proximal intestinal epithelium consists of columnar cells with microvilli towards the lumen and goblet cells. The enterocytes are joined at the apical surface by the junctional complex, including the evident desmosomas. Numerous lysosomes and some vesicles are evident in the upper cytoplasm of the cells, and a moderate amount of endoplasmic reticulum and lysosomes are scattered in the supranuclear cytoplasm. The epithelium becomes progressively thicker and the folds containing large numbers of goblet cells are fewer and shorter in the distal portion of the intestine. At the ultrastuctural level, the columnar cells of the tubular gastric glands have numerous clear vacuoles and channels. A moderate amount of pepsinogen granules are present in the stomach. The enterocytes of the intestinal mucosa display a moderate amount of endoplasmic reticulum and lysosomes, and long and regular microvilli.     

Hypergastrinaemia evoked by omeprazole stimulates growth of gastric mucosa but not of pancreas or intestines in hamster, guinea pig and chicken

Treatment of chickens, hamsters and guinea-pigs with the long-acting anti-secretagogue omeprazole resulted in elevated levels of serum gastrin. The chickens received 400 mumol/kg by i.m. injection once daily, the hamsters and guinea-pigs received the same dose by the oral route once daily. In all 3 species omeprazole raised the intragastric pH to 4, measured 12-14 h after the administration of the drug. After 10 weeks of treatment, trophic changes were observed in the stomach of hamster and guinea pig and in the proventriculus of chicken. The trophic changes were manifested in a greatly increased stomach weight and gastric mucosal mass. There were no trophic effects outside the stomach (or proventriculus). The results are in agreement with previous observations in the rat and support the view that long-lasting sustained hypergastrinaemia causes trophic changes in the stomach but not in the pancreas or in the intestines.     

Alternative routes of mucosal immunization in large animals

Mucosal immunization regimes that employ the oral route of delivery are often compromised by antigen degradation in the stomach. Moreover, tolerance or immunological unresponsiveness to orally delivered vaccine antigens is also a major problem associated with this route of immunization. Immunization by alternative routes including intrarectal (i.r.) and intranasal (i.n.) is becoming increasingly recognized in large animals for generating protective antibody responses at mucosal surfaces. These approaches are particularly useful in ruminant species which have four stomachs that can potentially interfere with antigen presentation to mucosal inductive sites of the gut. Modifications to enhance existing mucosal immunization regimes have also been explored through the use of alternative antigen delivery systems and mucosal adjuvants. The combination of alternative immunization routes and the use of appropriate antigen delivery systems appear to be a rational approach for providing protective immunity at mucosal surfaces. There has been a considerable amount of research conducted on evaluating the efficacy of emerging antigen delivery systems and novel adjuvants for improved immunity to mucosal immunization but very little of this work has been specific to the mucosal compartment of large animals. The aim of this review is therefore to assess the feasibility and practicality of using large animals (particularly sheep, cattle and pigs) for inducing and detecting specific immune responses to alternative mucosal routes of immunization.     

Gross morphology and histology of the alimentary tract of the convict cichlid Amatitlania nigrofasciata

The primary objectives of this study were to document the macroscopic and histological structure of the alimentary tract (AT) of the convict cichlid Amatitlania nigrofasciata, because there are no data available for this omnivorous freshwater fish of the family Cichlidae. The morphology of the AT of A. nigrofasciata resembles that of related species. While having morphological criteria of the AT typical of most omnivorous fishes, such as a blind sac stomach and medium length intestine, A. nigrofasciata also has some structural peculiarities: the oesophagus is lined by a uniform stratified squamous epithelial layer with interspersed goblet cells along its entire length. Additionally, it has well‐developed layers of the tunica muscularis including muscle fibre bundles that ascend into its mucosal folds. Occasionally, taste buds are present. In the transitional area between oesophagus and stomach, a prominent torus‐like closure device is present. The mucosa of the stomach cannot be divided into different regions according to mucosal and morphological properties. The simple pattern of intestinal loops of A. nigrofasciata has few variations, irrespective of sex, mass and length of the individual fish. The first segment of the intestine is characterized by the largest mucososerosal ratio and the most complex mucosal surface architecture. A distinction of midgut and hindgut was not possible in A. nigrofasciata due to lack of defining structural components as described for other fish species.     

Urease activity in the contents and tissues of the sheep, pig and chicken gastrointestinal apparatus.

Urease activity, expressed as mg N-NH3/g dry weight per 30 min at 25 degrees C, was determined in the various parts of the sheep, chicken and pig digestive apparatus. The results were as follows. Sheep: contents--rumen 1.25"/-0.09, reticulum 0.78+/-0.02, omasum 0.44+/-0.02, abomasum 0.002+/-0.001, duodenum 0.003+/-0.001, jejunum 0.18+/-0.03, ileum 0.42+/-0.03, caecum 1.34+/-0.11, colon 0.76+/-0.08, walls-rumen 0.88+/-0.16, reticulum 0.38+/-0.04, omasum 0.11+/-0.02, abomasum 0.01+/-0.002, ileum 0.092+/-0.01, caecum 0.14+/-0.03, colon 0.16+/-0.02. Chicken: contents--jejunum 0.028+/-0.009, ileum 0.043+/-0.013, caecum 0.17+/-0.03, colon and cloaca 0.04+/-0.013. Pigs: contents--jejunum 0.02+/-0.01, ileum 0.14+/-0.08, caecum 0.62+-0.12, colon 0.43+/-0.06. No urease activity was found in the walls of the digestive apparatus or the contents of the duodenum in chickens, or in the walls of the stomach and intestine and the contents of the duodenum in pigs. The results show that urease activity in the digestive apparatus of pigs and poultry is lower than in sheep. Inadequate urease activity in the digestive apparatus explains why chickens and pigs are significantly less capable than ruminants of utilizing urea nitrogen as a substitute for some of the protein in the diet.     

The development of the stomach in Clarias lazera and the intestinal absorption of protein macromolecules

Summary The development of the stomach of the teleost, Clarias lazera, during the early posthatching period, is described, and the developing stomach is compared with that of adult Clarias.The stomach develops in two distinct parts: the corpus, which differentiates first, and the pylorus. The corpus contains a mucous surface epithelium, arranged in folds, and a tubular gland system containing only one type of gland cell, to which the secretion of pepsinogen and HCl is attributed. The pyloric region does not contain tubular glands.From the ultrastructure of the gland cells, the ³H-thymidine labeling index, and the onset of acid production (as determined with pH indicators) it is concluded that a functional stomach is present in juveniles with a standard length of ± 11 mm (approximately 12 days after fertilization at 23–24° C).The ultrastructure of the intestinal epithelium has also been studied. The intestine consists of three segments, similar to those described for stomachless teleosts and a number of fish larvae. In larvae as well as in juveniles, the enterocytes of the second segment show pinocytosis of horseradish peroxidase, although in the juveniles the stomach has already developed. This second segment has the same relative length in all studied larvae and juveniles and is also present in adult Clarias.It is therefore concluded that the capacity to absorb protein macromolecules is not specifically related to the absence of a functional stomach in this teleost species.     

Existence of ghrelin-immunopositive and -expressing cells in the proventriculus of the hatching and adult chicken

Ghrelin was isolated from the rat stomach as an endogenous ligand for the growth hormone secretagogue receptor (GHS-R) and has been found in the gastrointestinal tract of many vertebrates. Although the sequence and structure of chicken ghrelin has recently been determined, morphological characteristics of ghrelin cells in the chicken gastrointestinal tract are still obscure. In this study, we investigated ghrelin expression and distribution of ghrelin-producing cells in the hatching and adult chicken gastrointestinal tract by RT-PCR, immunohistochemistry and in situ hybridization. Ghrelin mRNA expression was observed mainly in the proventriculus in the hatching chicken and in the proventriculus, pylorus and duodenum of the adult chicken by RT-PCR. Ghrelin-immunopositive (ghrelin-ip) cells in the proventriculus were located at the mucosal layer but not in the myenteric plexus or smooth muscle layer. The number of ghrelin-ip cells in the adult chicken was greater than that in the hatching chicken. Interestingly, in the adult chicken, the number of ghrelin-ip cells were almost the same as that of ghrelin mRNA-expressing (ghrelin-ex) cells; however, in the hatching chicken, the number of ghrelin-ex cells was greater than that of ghrelin-ip cells. These results clearly demonstrate that ghrelin-producing cells exist in the chicken gastrointestinal tract, especially in the proventriculus, from hatching to adult stages of development, as well as in mammals.     

Distribution of mucus glycoprotein in four compartments of lamb and sheep stomach

The regional distribution of mucus glycoprotein in lamb before weaning and sheep was studied. Mucus glycoprotein was present in the forestomach region of lamb and glandular stomach (abomasum) of lamb and sheep. Ester sulfates were found in all mucus glycoproteins obtained.     

Acetylcholinesterase and butyrylcholinesterase in the gut mucosal cells of various mammal species: distribution along the intestine and molecular forms

1. A cholinesterase activity was shown to be present in the homogenates of the gut mucosal cells from seven mammal species examined. 2. The distribution of the cholinesterase activity in the mucosal cells along the intestine differs from one species to another. This distribution is not correlated with that of the aminopeptidase which is a specific marker of the enterocyte plasma membranes. 3. Except rabbit, all the other species contain a (G4) globular tetrameric form and either a (G1) monomeric form (pig, ox) or a (G2) dimeric form (mouse, rat, sheep). Both (G1) and (G2) forms are found with the (G4) form in the mucosal cells of kitten and cat. The solubility characteristics of these various forms were studied by sucrose gradient centrifugations in the presence and the absence of 1% Triton X-100. 4. The mucosal cells from the studied species essentially possess either acetylcholinesterase (rabbit, kitten, cat) or butyrylcholinesterase (ox, pig, sheep, rat, mouse). These findings indicate that both enzymes probably present identical physiological functions in this cell type.     

泽陆蛙消化道组织学观察

采用解剖学和组织学的方法对泽陆蛙消化道各部分的形态和组织学结构进行了观察。泽陆蛙的消化道分为口腔、咽、食道、胃、十二指肠、回肠和大肠。各管壁都由黏膜层、黏膜下层、肌层和外膜组成。食道黏膜层有皱褶和纤毛,无杯状细胞;胃黏膜层有杯状细胞和胃腺,黏膜下层有血管分布;小肠具绒毛、杯状细胞和肠腺,大肠皱褶少,杯状细胞也少。     

Stomach motility in insulin-treated sheep.

The effect of insulin-induced hypoglycaemia on the motility of the reticulum, rumen and abomasum of sheep was investigated using small lightly inflated balloons connected to transducers and a multichannel recorder. The principle response recorded was an inhibition of reticulo-ruminal and abomasal motility, occurring in 'resting' cycles only, and not during eating or rumination. The only hypermotility recorded was that shown by the abomasum just before the onset of inhibition. Ruminating cycles were recorded as frequently during hypoglycaemia as in control periods, and showed no abnormality. The inhibition was reversed by intravenous glucose or adrenaline and by feeding or ruminating.     

THE ORIGIN OF STOMACH OIL IN THE PETRELS, WITH COMPARATIVE OBSERVATIONS ON THE AVIAN PROVENTRICULUS

The anatomy and histology of the proventriculus in several species of petrels were examined and compared with the conditions in other birds.
The proventriculus in petrels is comparatively very large and its mucosa is raised into longitudinal ridges; it thus has a much greater surface area than in other birds. The presence of lipoids other than triglycerides concentrated in large quantities, particularly in the outer parts of the epithelial cells of the proventricular glands of petrels, is demonstrated. Lipoids in the corresponding cells in other birds are minute in quantity.
The probability that these lipoids represent the stomach oil, or its precursor, immediately before secretion, is discussed and compared with other theories about the origin of the oil. The observations provide strong evidence, but not absolute proof, that the oil originates in the cells of the proventricular glands.
Suggestions about the possible function of petrel stomach oil are discussed. The oil may supplement the secretion of the preen gland; it may be an excreted by-product of the metabolism of excessively fat foods; or it may play an important part in water metabolism, especially in the nestling. Without further work, none of these theories can be upheld or refuted, and it is possible that all are partly correct, for they are not mutually exclusive.
Many petrels shoot stomach oil from the beak when they are disturbed. The possible origin of this habit from the escape reaction, found in many birds, of vomiting up the stomach contents when alarmed, is pointed out.