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At least 91 records · Page 5Linked to original sources
PubMed1998

Histopathological analysis of rat mesentery as a method for evaluating neutrophil migration: differential effects of dexamethasone and pertussis toxin.

In the present study, histopathological analysis of rat mesentery was used to quantify the effect of two anti-inflammatory agents, dexamethasone (Dex) and pertussis toxin (Ptx), on leukocyte migration. The intravenous injection of Dex (1 mg/kg) and Ptx (1,200 ng) 1 h prior to the intraperitoneal injection of the inflammatory stimuli lipopolysaccharide (LPS) or formyl-methionyl-leucyl-phenylalanine (fMLP) significantly reduced the neutrophil diapedesis (LPS: Ptx = 0.86 +/- 0.19 and Dex = 0.35 +/- 0.13 vs saline (S) = 2.85 +/- 0.59; fMLP: Ptx = 0.43 +/- 0.09 and Dex 0.01 +/- 0.01 vs S = 1.08 +/- 0.15 neutrophil diapedesis/field) and infiltration (LPS: Ptx = 6.29 +/- 1.4 and Dex = 3.06 +/- 0.76 vs S = 15.94 +/- 3.97; fMLP: Ptx = 3.85 +/- 0.56 and Dex = 0.40 +/- 0.16 vs S = 7.15 +/- 1.17 neutrophils/field) induced by the two agonists in the rat mesentery. The inhibitory effect of Dex and Ptx was clearly visible in the fields nearest the venule (up to 200 microns), demonstrating that these anti-inflammatory agents act preferentially in the transmigration of neutrophils from the vascular lumen into the interstitial space, but not in cell movement in response to a haptotactic gradient. The mesentery of rats pretreated with Dex showed a decreased number of neutrophils within the venules (LPS: Dex = 1.50 +/- 0.38 vs S = 4.20 +/- 1.01; fMLP: Dex = 0.25 +/- 0.11 vs S = 2.20 +/- 0.34 neutrophils in the lumen/field), suggesting that this inhibitor may be acting at a step that precedes neutrophil arrival in the inflamed tissue. In contrast to that observed with Dex treatment, the number of neutrophils found in mesenteric venules was significantly elevated in animals pretreated with Ptx (LPS: Ptx = 9.85 +/- 2.25 vs S = 4.20 +/- 1.01; fMLP: Ptx = 4.66 +/- 1.24 vs S = 2.20 +/- 0.34 neutrophils in the lumen/field). This discrepancy shows that Ptx and Dex act via different mechanisms and suggests that Ptx prevents locomotion of neutrophils from the vascular lumen to the interstitial space. In conclusion, the method described here is useful for quantifying the inflammatory and anti-inflammatory effect of different substances. The advantage of this histopathological approach is that it provides additional information about the steps involved in leucocyte migration.

Animals↗
PubMed2000

Development of an experimental apparatus for investigating lymphatic pumping activity of murine mesentery in vivo.

The present study has been attempted to establish a modified intravital microscope system for investigating murine lymphatic pumping activity in vivo and evaluate whether or not there is rhythmic pumping activity of murine mesenteric lymphatic vessels in vivo. We designed and constructed a custom organ chamber with a semicircular channel (8 mm in radius, 5 mm in width, 3 mm in depth), being suitable for the superfusing of murine mesentery in vivo. A marked lymphatic pumping activity was observed in the mesenteries of DDY mice. The maximal and minimal diameter and frequency in the pumping activity were 60.9 +/- 1.0 microm, 53.7 +/- 1.8 microm and 12.8 min(-1) (n = 5), respectively. Both NE (norepinephrine, 10(-8)-10(-6) M) and TEA (tetraethylammonium, 1-10 mM) caused dose-dependent constriction of the mesenteric lymphatic vessels in the mice. These findings suggest that a modified intravital microscope system with a specially designed and constructed edge-monitoring device enables us to investigate in vivo lymphatic circulation in murine mesenteries.

Animals↗
PubMed1975

Metastatic seeding along the small bowel mesentery. Roentgen features.

1. Intra-abdominal malignant seeding along the small bowel mesentery is roentgenologically identifiable. 2. The anatomic features of the small bowel mesentery and the pathways of flow of ascitic fluid along its peritoneal recesses determine the depostion and growth of seeded metastases. 3. Seeded deposits lodge particularly within the lower recesses of the small bowel mesentery and are reflected by typical changes involving distal ileal loops or the cecum. 4. These are characterized by (a) palisading, arcuate scalloped deflections or gross mass displacement of distal small bowel loops in the right lower quadrant, or (b) extrinsic indentations upon the medial and inferior contours of the cecum. Associated desmoplastic reaction may result in tethering of mucosal folds and angulated fixation of bowel loops.

Adenocarcinoma, Mucinous↗
PubMed1984

Computed tomography of the normal mesentery.

Thirty patients were studied to evaluate the CT appearance of the normal mesentery and its vasculature. Mesenteric vessels were identified by determining their relations to segments of the small bowel and colon in the 30 patients. Jejunal and ileal branches supplying small bowel were identified in all patients. The ileocolic and right colic branches of the ascending colon were identified in 27 and 26 patients, respectively; middle colic vessels were identified in 29 patients. Left colic branches were identified in only 14 patients; sigmoid branches were identified in 23 patients. The vessels showed a characteristic wavy appearance as they coursed through mesenteric fat. The average attenuation of the mesenteric fat was -117.4 +/- 7.9 H. Normal lymph nodes were not routinely identified within the mesentery. Various pathologic processes altered the normal appearance of the components of the mesentery.

Adipose Tissue↗
PubMed2002

Distribution of ganglionic sympathetic neurons supplying the subcutaneous, perirenal and mesentery fat tissue depots in the pig.

Previous morphological studies revealed that the adipose tissue is innervated by adrenergic nerve fibers. Furthermore, physiological studies showed that the metabolism of adipose tissue is controlled by the adrenergic component of the nervous system. However, nothing is known on the sources of innervation of different fat tissue depots. Therefore, we decided to study the distribution of ganglionic sympathetic neurons innervating adipose tissue in the pig by means of a retrograde tracing method. We used 9 male and 9 female pigs of approximately 50 kg body weight. The retrograde tracer, Fast Blue (FB), was injected into the subcutaneous, perirenal and mesentery fat tissue depots. Results of the present study showed that numerous centers of the sympathetic nervous system innervate adipose tissue in the pig. FB+ neurons projecting to the subcutaneous fat tissue were placed in the thoraco-lumbar region of the sympathetic chain ganglia (SChG). However, neurons supplying perirenal and mesentery fat tissue depots were found in both the SChG and prevertebral ganglia (PVG). We conclude that different adipose tissue depots (subcutaneous, perirenal and mesentery) have different sources of innervation and that there is no significant difference in the distribution of neurons innervating adipose tissue in male and female pigs.

Adipose Tissue↗
PubMed2000

[Malignant mesenchymoma of mesentery. A controversial entity].

We report a case of malignant mesenchymoma developed in the mesentery in a 62-year-old man with no past history. It was an huge mass in the mesentery of the ileum. The tumor was composed of areas of chondrosarcoma and rhabdomyosarcoma in addition to an undifferentiated fusiform component. Malignant mesenchymoma is a rare sarcoma occurring preferentially in the retroperitoneum or the thigh. The location in the mesentery is exceptional. Malignant mesenchymoma is discussed more particularly with dedifferentiated liposarcoma with heterologous elements. The patient is alive without recurrence three years after surgery.

Abdominal Neoplasms↗
PubMedDate not supplied

Connective tissue repair in zinc deficiency. An ultrastructural morphometric study in perforated mesentery in rats.

OBJECTIVE: To quantify measures of healing in zinc-deficient and healthy rats. DESIGN: Randomized study. MATERIAL: 30 male Sprague-Dawley rats. INTERVENTIONS: Zinc deficiency was induced in half the rats. All rats underwent laparotomy and standard perforations were made in the small intestinal mesentery with a scalpel. At 1, 3, 5, 7 and 10 days after operation 6 rats were killed by overdose of anaesthetic agents and the specimens of the mesentery were fixed. MAIN OUTCOME MEASURES: Measurement of cellular volume density, surface density of the rough endoplasmic reticulum, and surface density of the plasma membrane. RESULTS: Perforations started to close on day 4, and most were closed by day 10. Cellular volume density reached its peak between days 3 and 5, as did surface density of rough endoplasmic reticulum. There were no significant differences between the two groups for either measurement. The surface density of the rough endoplasmic reticulum, however, was significantly higher in controls than in zinc deficient animals on days 3-10 (p less than 0.001). The surface density of the plasma membrane was significantly higher in zinc-deficient animals on days 1-3 (p less than 0.04), and in control animals on days 5-10 (p less than 0.01). CONCLUSIONS: Protein synthesis and formation of scar tissue were slightly lower in the zinc-deficient animals, and the higher plasma membrane surface density implies that contraction may be an important part of healing in the small intestinal mesentery in rats.

Animals↗
PubMed1991

Light and electron microscopy of the structural organization of the tissue-lymphatic fluid drainage system in the mesentery: an experimental study.

Supplementing vital microscopy and histophysiology, we examined using combined light and electron microscopy the tissue fluid-lymphatic drainage system of the mesentery isolated from guinea pigs, rabbits, and tree shrews. In silver impregnated tissue, different types of lymphatics and blood vessels were able to be distinguished along with argyrophilic and argyrophobic structures in the connective tissue. Some initial lymphatic pathways were interrupted by non-endothelialized tissue zones thus forming separate but discrete vascular "islands". After carbon labeling of the lymphatic collectors, carbon particles were seen to escape from the initial lymphatic lumen at various sites. Electron microscopy revealed wide apertures in the lymphatic endothelial cells of these microvessels. These morphological findings support the concept of an "open" prelymphatic-lymphatic system in the mesentery. The special histometrical features exhibited by a flat membranous organ like the mesentery are discussed in terms of physiologic function of mesenteric tissue fluid transport.

Animals↗
PubMed1990

Ultrastructural aspects of and observations on the permeability of the rat mesentery to colloidal iron.

In works already published, it was made clear that many researches were interested in the absorption phenomena, permeability and structure of the visceral mesothelial tissue. Attention was concentrated on the mesentery and observations were made using the application of lanthanum nitrate and osmium-amine. The penetration of lanthanum nitrate is impeded by the basement membrane situated between the connective and mesothelial tissues. The heavy salt moves through and not between the mesothelial cells by passive diffusion. No reaction was observed in general with osmium-amine, with the exception of a few cases. In those instances, the osmium-amine reacted not only in the outer surface of the mesentery, but also penetrated with no visible reaction all the way to the connective tissue where it was detected in the elastic layer. In this paper, the colloidal iron was employed using different techniques, and depositions were detected in the surface of the mesentery, in the mesothelial cells and also in the connective tissue. A final conclusion that the permeability of different layers of tissues is of great variety and has a definite capacity for selectivity is suggested.

Absorption↗
PubMed1989

[Mechanical ileus caused by strangulation of the small intestine in a left paraduodenal hernia and in a defect in the root of the mesentery].

A case of mechanical ileus caused by small intestine strangulation into a left paraduodenal hernia and through a circular defect in the root of the mesentery is presented. Whereas left paraduodenal hernia is very rare in the surgical casuistics, its occurrence associated with strangulation through a defect in the mesentery has not been documented up to now to the author's knowledge. The true cause of strangulation ileus was found at operation. Reduction of the intestinal loop from the defect in the root of the mesentery was followed by reduction of the loops from the hernial sac. Both apertures were repaired with great caution using individual sutures without resection of the hernial sac. The early and late postoperative evolutions were uneventful.

Adult↗
PubMed1989

Distensibility of single capillaries and venules in the rat and frog mesentery.

The distensibility characteristics of single microvessels in the mesentery of frogs and rats has been determined by a new technique capable of resolving a change in radius of about 0.01 micron in vivo. Two water insoluble immiscible oils were micro-injected into occluded segments of the vessels. Since the volume of the oil remained constant, the position of the interface at different applied pressures could be used to determine changes in vessel diameter. The stress/strain relationship of capillaries and venules in the frog mesentery and venules in the rat mesentery were determined and found to be similar to each other. Vessel diameters increased by up to 15% over the whole pressure range used but in a markedly non-linear manner, stiffening at higher strains. It is suggested that the basement membrane has the appropriate properties to explain this behaviour.

Animals↗
PubMed1985

Inhibitory effects of mannose and N-acetylneuraminic acid on the envelope and the adherence of a Neisseria gonorrhoeae isolate to rabbit mesentery.

Sugars and sugar derivatives were investigated as potential inhibitors of adherence of Neisseria gonorrhoeae; in this experiment rabbit mesentery was used as a reliable and convenient tissue. The adherence of N. gonorrhoeae isolate 2299 was reduced by half and more, as compared to controls, in the presence of 1,0 mg N-acetylneuraminic acid or D-mannose per ml of culture media, but not by the other sugars tested. Our data suggest that the N. gonorrhoeae isolate used in this work has mannose-binding related activity which participates in the process of its adherence to rabbit mesentery cells. In addition we observed that pretreatment of rabbit mesentery with concanavalin A, but not with peanut and wheat germ agglutinins, markedly decreased the adherence of gonococci as determined by microscopic counts of adhering bacterial cells.

Adhesiveness↗
PubMed1985

[Development of the reactivity of the microcirculatory system of the rat mesentery during sexual maturation].

Biomicroscopy was employed to study the time-course of microcirculatory reactivity in rat mesentery under the influence of adrenaline solution from the 3d to the 13th week of development. Variation in the microcirculatory reactivity in the mesentery in ontogenesis is associated with an increase in the sensitivity of microvessels to the action of vasoactive substances and with the organization of the microcirculatory bed becoming more complicated. Three stages were revealed in the development of microvascular reactivity in the course of formation of mesenterial microcirculation: early (3-5 weeks), characterized by relatively low sensitivity of microvessels; intermediate (7-8 weeks) marked by a progressive increase in microvascular sensitivity; mature (starting from the 13th week) characterized by the appearance of the definitive reaction pattern.

Aging↗
PubMed1977

[Tumors of the mesentery of the small intestine].

The clinical picture of solid tumors of the intestinal mesentery is varied and depends on the character of growth (benign, malignant), size and anatomical variants of tumor localization in the mesentery. Sometimes, the tumors concerned can induce pseudosyndrome of acute abdomen or inflammation of the adjacent organ secondary involved by tumor. Among complications induced by tumor are as follows: intestinal hemorrhage, peritonitis and acute or partial intestinal obstruction. The roentgenological picture of intestinal mesentery tumors shows some characteristic features. Eight observations of the author are reported.

Adolescent↗
PubMed1984

[A case of malignant schwannoma of the mesentery in a patient with von Recklinghausen's disease].

A 23-year-old man with Von Recklinghausen's disease was admitted because of abdominal pain. The preoperative diagnosis was malignant mesenteric tumor. Laparotomy was done and the tumor was located in the mesentery of the ileum which showed numerous tortuous cords or bulbous projections from the surface. Partial resection of the involved ileum and the mesentery was performed. Histological examination revealed plexiform neurofibroma and malignant Schwannoma of the mesentery. It is very difficult to preoperatively diagnose early associated lesions of Von Recklinghausen's disease. Therefore, careful examination of the GI tract is important so that earlier therapy can be carried out.

Adult↗
PubMed1984

[Mesentery collector valves in the guinea pig: morpho-functional aspects].

In guinea pig mesenterial lymph vessels there are many bicuspid valves, which determine the flow centralwards of lymph. Our observations, based on the study of 52 guinea pig lymph collectors, demonstrated a different number of valves on different parts of each vessel. In fact we found more valves in the part near the intestinal wall and the mesenterial lymph node than in the middle part of the vessel. Besides we measured the time of flow in these different portions by Indian ink injection and we found a correlation between valve number and flow. In fact the time of flow decreases with the increase of the number of valves the shortest being near the intestinal wall and the mesenterial lymph node and the longest being in the middle part of the collectors. The experimental data indicate that the valves have an important role in the lymph circulation because they favour the flow lymph velocity.

Animals↗
PubMed1981

A new method for the simultaneous presentation of low and high magnifications of microscopic specimens: application to in vivo studies of mesenterial capillaries.

By combining an incident light microscope (C. Zeiss) with an inverted camera microscope (ICM 405, C. Zeiss) having a common optic axis, it was possible to present simultaneously two microscope images of one object. These images were recorded by two television cameras and displayed on a single monitor with the aid of a video mixer (Pieper, Schwerte). This method was applied to intravital microscopy of mesenterial capillaries (rabbit and frog). It allowed the choice of a vascular network as an overview with the incident light microscope from which a suitable capillary segment for an electrical stimulation experiment could be selected and magnified with the transmitted light microscope. The results of its application provided proof that electrically induced constrictions in capillaries are independent of proximally or distally occurring vascular reactions. Capillaries of mesenteries in rabbits and frogs were stimulated with direct currents ranging from +0.015 micro A to +20 micro A. The constrictions were found to be reversible and reproducible. In addition capillary constrictions could also be produced by topical application of histamine and serotonin droplets applied to the surface of the mesentery. These observations may help to resolve the question of whether capillary contractility in the sense of Stricker (1865, 1876) is a biological mechanism.

Animals↗
PubMed1996

Acute small intestinal injury associated with hematomas in the mesentery of four horses.

Four horses were evaluated for clinical signs consistent with small intestinal disease. During exploratory surgery, primary hematomas in the mesentery were found in 2 horses. The third horse developed a hematoma secondary to a mesenteric rent, whereas in the fourth horse, a hematoma developed secondary to strangulation of the bowel by a mesenteric lipoma. Two horses were euthanatized at surgery, because the extensive nature of the hematoma precluded ligation and there was substantial risk of continued hemorrhage postoperatively. The remaining horses recovered from surgery but developed complications. One horse developed functional ileus and required a second surgery to decompress the bowel, whereas the second horse eventually was euthanatized for severe, recurrent signs of colic. Clinical signs and management of small intestinal lesions related to volvulus, epiploic entrapment, intramural hematoma, mesenteric rent, and intussuception have been described. To our knowledge, reports of small intestinal infarctions secondary to hematomas in the mesentery have not been published. Primary hematomas in the mesentery should be included in the differential diagnoses for horses examined for signs of depression, anorexia, and progressive signs of colic.

Acute Disease↗