Caudal Mesenteric Artery Research Articles

Study on Cranial and Caudal Mesenteric Arteries in Opossum (Didelphis albiventris)

SUMMARY : The objective of this study is to describe the cranial and caudal mesenteric arteries in 10 opossuns after Neoprenelatex injection. The cranial mesenteric artery arises from the abdominal aorta, caudally to the celiac trunk, originating the caudal duodenalpancreatic artery, middle and right colic, jejunal and ileocecocolic arteries. The caudal mesenteric artery arises from the aorta, craniallyto the external iliac arteries, originating the cranial rectal and left colic arteries. KEY WORDS: Anatomy; Opossum; Mesenteric arteries. INTRODUCTION Considering that the anatomical knowledge is necessary tounderstand the biological functions, a macroscopic study on thecranial and caudal mesenteric arteries was carried out, aiming atincreasing the anatomy knowledge compared with other animals.Studies with rats carried out by Greene (1955), Farris &Griffith (1949) and Cook (1965) stated that in these animals th eupper mesenteric artery is a great vessel that comes from theaorta abdominal portion, originating a lower pancreatic-duodena lbranch which extends to the pancreas and duodenum and severalbranches to the jejunum and ileum, cecum and colon.Barone

Evaluation of the accuracy of a wireless pressure sensor in a canine model of retrograde-collateral (type II) endoleak and correlation with histologic analysis

The utility of intra-aneurysmal pressure determination is dependent on the ability to measure pressure in the presence of endoleak and thrombosis. In this study, the accuracy of a CardioMEMS wireless pressure sensor (CardioMEMS, Atlanta, Ga) transducer in the presence of thrombus associated with type II endoleak was measured. Type II endoleaks were created in four mongrel dogs by implanting four collateral arterial side branches (lumbar and caudal mesenteric arteries) as a Carrel patch onto a 3-cm prosthetic polytetrafluoroethylene abdominal aortic aneurysm (AAA). The aneurysm was excluded 2 weeks later from antegrade perfusion by a stent graft. The wireless pressure sensor was positioned in the AAA external to the stent graft. A Konigsberg intraluminal solid-state strain-gauge pressure transducer (Konigsberg Instruments, Pasadena, Calif) that is accurate in the presence of thrombus served as the control to determine AAA pressure. Both of the transducers were implanted on the luminal surface of the aneurysm, 180 degrees opposite from the Carrel patch and endoleak channel. Intra-aneurysmal pressure resulting from the type II endoleak was measured twice daily for 4 weeks using both transducers. A total of 56 pre-exclusion and 224 post-exclusion distinct pressure determinations were made. Intra-aneurysmal pressure was indexed to the systemic pressure that was simultaneously measured by a strain-gauge pressure transducer implanted in the native aorta. Histologic analysis of the aneurysm contents was performed with hematoxylin and eosin. The intra-aneurysmal systolic, mean, and pulse pressures produced by the type II endoleak were significantly lower than systemic pressure in all animals and were < 60% of systemic pressure (P < .001). Close correlation between the wireless transducer and the control strain-gauge transducer was observed (R = 0.83, P < .001). Arteriography and Doppler ultrasound documented retrograde flow through the aneurysm side branches and persistent endoleak patency up to the time of euthanasia. Pathologic analysis demonstrated the endoleak channel to be patent and separated from the transducers by thrombus, which surrounded both transducers. Intra-aneurysmal pressure generated by type II endoleaks may be accurately measured through thrombus using a wireless pressure sensor in the canine model. The wireless sensor has the potential for clinical applicability in diagnosing and characterizing type II endoleaks.

Artérias mesentéricas cranial e caudal em aves (Gallus gallus) da linhagem Cobb 500

Estudaram-se as origens, ramificações e distribuições das artérias mesentéricas cranial e caudal em 30 aves (Gallus gallus) da linhagem Cobb 500, machos, com idade entre 5 e 6 semanas. Os espécimes tiveram seus vasos arteriais preenchidos com solução aquosa corada de Neoprene Látex "450" a 50% e a seguir foram fixados em solução aquosa de formaldeído a 10%. A artéria mesentérica cranial emergiu da face lateral direita da aorta descendente caudalmente à artéria celíaca e através das artérias ileocecal, jejunais e ileais distribuiu-se pelo jejuno, íleo, cecos e reto, terminando próximo ao divertículo vitelino. A artéria mesentérica caudal originou-se da face ventral da aorta descendente e após curto trajeto bifurcou-se em ramos cranial e caudal, distribuindo-se pelo reto, cloaca e bolsa cloacal. Evidenciaram-se anastomoses entre ramos da artéria mesentérica cranial e entre ramos desta e ramos das artérias mesentérica caudal e celíaca.

First description and morphology of haemal nodes in piglets(Sus scrofa domestica)

In this study, the presence of haemal nodes, previously recognised especially in ruminants, was determined for the first time in piglets. The morphology of haemal nodes located in the abdominal cavity of seven piglets was studied by gross inspection and by histological methods. Haemal nodes reddish in colour and oval or round in shape were observed on the thin branches originating from the caudal and cranial mesenteric arteries. These nodes, having connection only with blood vessels, were covered with a thin connective tissue capsule. The haemal nodes had a hilus at the entrance of which large blood vessels were seen. These blood vessels extended into the inside of the nodes through trabeculae. Afferent and efferent lymph vessels were not observed in the haemal nodes. The nodes contained many sinuses formed by reticular fibres and reticular cells and filled by red blood cells. In the haemal nodes, lymphocytic infiltration was more commonly seen than lymph follicles.

A canine model to study the significance and hemodynamics of type II endoleaks 1

The clinical significance of Type 2 endoleak after endovascular repair of abdominal aortic aneurysms (AAA) remains incompletely delineated. This study describes the development of a novel canine model that allows for continuous monitoring of intraaneurysmal pressure in the setting of Type 2 endoleak. Infrarenal AAA were created in 10 mongrel dogs by implanting a prosthetic aneurysm containing an intraluminal, solid-state, strain gauge pressure transducer which is able to measure pressures in both solid and liquid media. A segment of native aorta with two or more patent side branch vessels was reimplanted into the prosthetic aneurysm using a Carrel patch. Four animals had two lumbar vessels implanted; two had two lumbar vessels and the caudal mesenteric artery implanted, and four control animals had no vessels reimplanted. Retrograde flow in the aneurysmal side branches caused a Type 2 endoleak after the aneurysm was excluded from antegrade flow by deploying a stent graft. Both systemic and intra-sac pressures were measured daily for up to 90 days after endovascular exclusion and indexed to systemic pressure. Endoleak patency and flow were assessed with digital subtraction angiography, duplex ultrasound, and cine-magnetic resonance angiography (MRA). Histological characterization of the intraaneurysmal contents was performed. Before endovascular exclusion, the systolic, mean arterial, and pulse pressure within the aneurysmal sac closely matched that of the systemic circulation (systolic, 0.96 +/- 0.22; mean, 0.94 +/- 0.21; pulse pressure, 0.97 +/- 0.22) (R value, 0.97). Endovascular exclusion in animals with no collateral side branch vessels resulted in no endoleak and significantly reduced intraaneurysmal pressure when compared to systemic pressure, with systolic, mean arterial, and pulse pressure 0.172 +/- 0.05, 0.137 +/- 0.05, and 0.098 +/- 0.02, respectively (P < 0.001). In animals with Type 2 endoleaks, the pressures were lower than systemic pressure, but statistically significant in their difference from the control group. The systolic pressure of those with Type 2 endoleaks was 0.702 +/- 0.048; mean arterial pressure was 0.784 +/- 0.028, and pulse pressure was 0.406 +/- 0.031 when indexed to systemic pressure (P < 0.001). Cine-MRA and Duplex ultrasound documented persistent patency of the Type 2 endoleaks throughout the study period in animals with multiple side branches. Intraaneurysmal pressure in the setting of Type 2 endoleaks may be accurately determined using this canine model. Intraaneurysmal pressure is maintained at a significant level in the context of this retrograde collateral perfusion, suggesting that persistent Type 2 endoleaks are of clinical significance. This model may serve to allow further evaluation and characterization of Type 2 endoleaks.

Embryonic origin of the caudal mesenteric artery in the mouse.

It is commonly held that the caudal mesenteric artery (CaMA, or inferior mesenteric artery in humans) arises in the same manner as the celiac and cranial mesenteric artery (CrMA, or superior mesenteric artery in humans), i.e., from the remodeling of the vitelline system of arteries that surrounds and supports the yolk sac. Conflicting evidence about the precise manner in which the CaMA arises was presented in studies of the luxate syndrome (Carter: J. Genet. 1954;52:1-35) and sirenomelia (Schreiner and Hoornbeek: J. Morphol. 1973;141:345-358) in the mouse. These studies suggested that the CaMA arises from the remodeling of the medial umbilical arterial roots. Later studies of blood vessel development in the hindlimb of the Dominant hemimelic mouse (Gest: Anat. Rec. 1984;208:296; Anat. Rec. 1987;218:49A; Gest and Roden: Anat. Rec. 1988;220:37-38A) also supported the results of the previous studies. The present investigation tests the hypothesis that the CaMA arises as a result of the regression and remodeling of the medial umbilical arterial roots. Vascular corrosion casts of 9.5-13.5-day-old mouse embryos were observed by scanning electron microscopy (SEM). The results of the present investigation agree with the aforementioned studies. The medial umbilical roots initially conduct the blood to the placenta. On days 10-12 the medial umbilical roots regress and remodel into the CaMA, while the lateral umbilical roots take over the blood supply to the placenta. On the basis of our results, we conclude that the CaMA arises from the medial umbilical roots and not from the remodeling of the vitelline system of arteries, as previously assumed.

Comportamento das artérias extramurais do útero de cães sem raça definida (Canis familiaris - Linnaeus, 1758)

The present study involved thirty femeale adult dogs coming from the kennel of the Veterinary Hospital of the Federal University of Uberlândia, Minas Gerais, Brazil. The thoracic cavity of the animal was opened and the aorta astery (thoracic part) was locared and canulated. A 450 Neoprene latex solution was used to injet the aorta astery in caudal direction. The specimens were then fixed in a 10 % formol aqueous solution. The results showed that the ovaric, uterine and vaginal arteries supply the uterus as follows : (1) the ovaric artery, in all the cases, arose from the aorta artery, either cranially to the caudal mesenteric artery (98,33%) or at same level of this artery (1,67%). In 83,33% of the cases, it gave off a branch to the uterine corns, which was distributed on the dorsal (8,00%), on the ventral (12,00%) and ond the both (80,00%) surfaces. In addition, two uterine branches distributed on the ventral (66,67%) and the dorsal (33,33%) surfaces were found in 10,00% of the cases; (2) the uterine artery, in all the cases, arose from the vaginal artery. In all the specimens the artery uterine supplied the uterine corns, with the ventral surfaces receiving greater mean number of branches than the dorsal surface. Concerning the uterine body the mean number of branches from the uterine artery showed to be greater on the dorsal surface. In 70, 00% of the cases, the uterine cervix received branches from directly from the uterine artery, with greater number of these arterial vessels being found on the ventral surface.

The Intermesenteric Plexus in the Pigeon (Columba livia GM)

Using the thiocholine method and histological techniques the intermesenteric plexus of the pigeon was studied. The intermesenteric plexus of this species is a plexo-ganglionic structure with several (five to seven) ganglia and nerve fibres. The ganglia have an oval-, spindle- or star-like shape. Single nerve cells along the nerve fibres were observed. The intermesenteric plexus of the pigeon is situated on the ventrolateral surface of the aorta, between the cranial mesenteric artery and caudal mesenteric artery. The connections between the intermesenteric and other vegetative plexuses (coeliac plexus, mesenteric inferior plexus) and the pelvic nerve were observed.

Origens e ramificações das artérias mesentéricas cranial e caudal em fetos de caprinos da raça Saanen (Capra hircus -- Linnaeus, 1758)

Estudaram-se as origens e ramificacoes das arterias mesentericas cranial e caudal que se destinam as visceras abdominais, em particular aos estomagos e intestinos de caprinos da raca Saanen, com o intuito de conhecer os pormenores da circulacao arterial destes orgaos. Utilizaram-se, para tanto, 30 fetos (19 machos e 11 femeas). Adotou-se a metodologia de dissecacao dos vasos, previamente injetados com solucao de latex Neoprene 450, corada com pigmento especifico. A arteria mesenterica cranial originou-se da arteria aorta descendente abdominal, caudalmente a arteria celiaca em 93,33% dos casos e em tronco comum (tronco celiacomesenterico) em 6,66% dos casos, e emitiu, a seguir, os seguintes ramos: ramos adrenais esquerdos (100%), ramos adrenais direitos (100%), ramos pancreaticos (96,66%), arteria pancreatico-duodenal caudal (100%), arteria colica media (96,66%), arteria ileocecolica (100%), arterias jejunais (100%) e arteria pancreaticocolica (3,33%). A arteria mesenterica caudal originou-se da face ventral da arteria aorta descendente abdominal em 100% das observacoes e emitiu as arterias colica esquerda e retal cranial em 100% dos casos e, em 3,33% das preparacoes, deu origem a arteria testicular esquerda.

Irrigação da bolsa cloacal, em aves reprodutoras, da linhagem Peterson (Gallus gallus domesticus)

Estudaram-se em 30 exemplares de matrizes pesadas de corte machos da linhagem Peterson (Gallus gallus domesticus), com idade variando de 10 a 12 semanas, a origem, o numero e a ordenacao dos vasos arteriais da bolsa cloacal, um dos orgaos responsaveis pela producao de respostas humorais nas aves. Mediante injecao dos contingentes arteriais com solucao aquosa de Artecola® a 50%, via arteria isquiatica direita, a dissecacao evidenciou que em 100% dos casos a bolsa cloacal era irrigada por 1 ou 2 arterias bursocloacais; em 16,66% dos casos por 1 ramo direto oriundo das arterias cloacais; em 6,66% dos casos por 2 ramos diretos da arteria caudal mediana e em 3,33% dos casos por 1 ramo bursal da arteria mesenterica caudal. O numero de vasos, independentemente da sua origem, variou de 2 a 5 com maior frequencia de 2 vasos. A distribuicao dos vasos se fez de maneira propria para cada peca.

Os arranjos configurados pelas artérias mesentéricas cranial e caudal no pato doméstico (Cairina moshata)

Herewith we studied the pattern disposition of the cranial and caudal mesenteric arteries in 30 domestic ducks (Cairina moshata), 20 males and 10 females. Latex 650 was injected in the arterial system and then the samples were fixed in 10% aquous formol solution for later dissection. The cranial mesenteric artery originates as a single vessel from the descendent aorta at the 6th or 7th rib, in a position immediately caudal to the celiac artery. Close to the ileo-cecum-colic junction, it subdivides itself primarily in 3 branches: the first branch gives away a vessel that goes to the colorectum, forming anastomosys with the caudal mesenteric artery. The second branch follows as a trunk to the jejunal arteries, that vary in numbers from 8-20. Finally the third branch is directed to the main and final portions of the right cecum and also ileo, vascularizing them. Concerning the pattern followed by the caudal mesenteric artery, we observed that it originates from the aorta as a single vessel, next to the caudal portions of the kidneys. In all observed samples the caudal mesenteric artery divides itself in 2 branches: a cranial one, that by itself gives away two smaller vessels to the mesorectum and a caudal branch that vascularizes the final portion of the rectum, cloacal bursa and cloaca.

The blood supply to the abdominal and pelvic regions in talpids: character analysis and implications for specific relationships among Insectivora

The morphology of the abdominal and pelvic arterial system was analysed in two talpid species, the common mole ( Talpa europaea) and the Pyrenean desman ( Galemys pyrenaicus). Animals were studied by injection of coloured latex solution into the aorta by cannulation through the left ventricle of the heart, and subsequent dissection under a surgical microscope. In spite of the intra- and interspecific variation observed in the main abdominal and pelvic vessels examined, the general arrangements observed in talpids are consistent with the patterns described in other Insectivora, such as Soricinae and Crocidurinae. Interspecific morphological comparisons within the Insectivora and with representatives of other mammal orders revealed that the origin and arrangement of certain arteries, such as the renal, gonadal, caudal mesenteric, and median sacral arteries are clearly uncorrelated with function and phylogeny. Similar conclusions can be extended to the common or separate origin of the cœliac and the cranial mesenteric arteries. In contrast, other specific arterial traits can be interpreted from a functional and/or evolutionary standpoint. We discuss these implications for the following characteristics: the absence of gastroepiploic arteries; the presence of double lienal arteries and right gastric artery; the course of the cranial mesenteric artery; the presence of the ductus deferentis artery; and the origin of the cranial gluteal, deep iliac circumflex, and medial and lateral femoral circumflex arteries. Phenetic relationships among Soricomorpha were evaluated by cluster analysis. Congruence between the phenogram obtained and an accepted evolutionary hypothesis corroborates the phylogenetic significance of some arterial arrangements.

Regional differences in noradrenaline-induced release of adenosine triphosphate from rat vascular endothelium.

We examined the release of endogenous adenyl purines such as adenosine triphosphate (ATP), ADP, AMP and adenosine from the caudal artery (CA), saphenous artery (SA), renal artery (RA), mesenteric artery (MA), pulmonary artery (PA) and thoracic aorta (TA) of rats, using high-performance liquid chromatography fluorescence detection. Noradrenaline induced the release of adenyl purines from these blood vessels. The total amount of adenyl purines release induced by noradrenaline from the CA was considerably larger than that from the TA. The rank order of the amount of adenyl purines released from the six blood vessels was CA>SA>RA>MA>PA> or =TA. The noradrenaline induced release of adenyl purines from the CA was significantly reduced by the removal of the endothelium. Noradrenaline also induced the release of adenyl purines from cultured endothelial cells of the CA and TA. The total amount of adenyl purines released from the former blood vessel was much larger than that from the latter. These results suggest the existence of vascular endothelial cells that are able to release ATP by an alpha1-adrenoceptor mediated mechanism, and that these cells are not homogeneously distributed in the vasculature.

Arterial vascularization of the abdominal and pelvic regions in the degu, Octodon degus (Rodentia, Octodontidae)

The abdominal and the pelvic arterial supply of the degu, Octodon degus, were described in 19 specimens (10 males and 9 females) from a laboratory strain. Animals were injected through the left ventricle of the heart with coloured latex solution and subsequently dissected under a surgical microscope. The arrangement and variations of the visceral and muscular arteries were described. Comparative analysis among rodents revealed that, even though there was a wide range of interspecific variation in the characters considered, there were several constant anatomical features with phylogenetic value. In this sense, results on the degu and the guinea pig, Cavia porcellus, showed that these hystricognaths share particular features that differentiate them from the sciurognaths analysed to date. The distinguishing characteristics between these two groups of rodents were found in the arrangement of the coeliacomesenteric trunk, and in the cranial abdominal, right gastric, caudal mesenteric, and deep circumflex iliac arteries. The phylogenetic meaning of particular angiological features in rodents were commented.

Transanal Intracolonic Pulse Oximetry as a Means of Monitoring the Adequacy of Colonic Perfusion

Techniques for determining intraoperative compromise in colonic blood flow during aortic reconstruction are inadequate. We investigated the use of transanally recorded oxygen saturation in a porcine model. A Nellcor RS-10 reflectance pulse oximeter probe was attached to the balloon of a Foley catheter and passed transanally to record the oxygen saturation of the sigmoid colonic mucosa. The blood flow rate of the caudal mesenteric artery (CMA) was recorded with a Transonic ultrasonic flowmeter. CMA flow and transanal O2 saturation were recorded simultaneously as CMA flow was progressively decreased by compression of the infrarenal aorta. With unimpeded blood flow the mean O2 saturation in the distal colonic mucosa was 92.9% ± 2.8. As CMA flow was progressively decreased to 20% of baseline flow, there was a linear decrease in colonic O2 saturation (r = 0.91 P < 0.01). At 20% of basal CMA flow, colonic O2 saturation was 54.0% ± 4.1. Below 20% of basal CMA flow there was an abrupt loss of signal from the pulse oximeter. This study suggests that transanal pulse oximetry would provide a simple means of continuously monitoring the adequacy of distal colonic blood flow intraoperatively and may prove to be useful during aortic reconstruction when there is concern about the adequacy of blood flow to the distal colon.

Experimental and clinical studies on ischemic lesions of the large intestine

To clarify the pathogenesis and endoscopic features of ischemic lesions of the colon, experimental ischemia was induced in dogs by arterial ligation, gelfoam injection, and clipping. In addition, clinical and endoscopic features of ischemic lesions in ischemic colitis cases in human were studied. In the experimental model, arterial ligation including marginal arteries frequently induced erosions in the large intestine, whereas ligation of the colic artery alone did not induce apparent mucosal lesions of the large intestine. Gelfoam injection to produce thrombi into caudal mesenteric artery or middle colic artery induced ulcers with a high rate of incidence and frequently accompanied by intestinal perforation. Temporal impairment of blood supply by arterial clipping produced erosion, but not ulcers. A high incidence of erosion was obtained in a group that underwent clipping for a prolonged period and a group of receiving Alosenn. Mucosal blood flow measured by the hydrogen gas clearance method was significantly decreased at 1 hr and 4 hr after gelfoam injection compared with those after arterial ligation. In human cases of ischemia following arterial surgery, endoscopic features were similar to those lesions of the experimental ischemia induced by gelfoam injection. These results suggest that thrombi in peripheral small arteries may play a major role in the pathogenesis of ischemic lesions of the large intestine.

Arrangement of the branches of the aorta abdominalis in the wood mouse (Apodemus sylvaticus).

Data on the distribution and variation of the abdominal arteries in the wood mouse, Apodemus sylvaticus, are given. Seventy specimens (44 males and 26 females) caught in the field were analyzed by injection of green latex solution and dissection. The general branching pattern of the aorta abdominalis is similar to those described in other rodents. There are certain differences, however, especially in the branching of the coeliac trunk, the origin of the genital arteries and the arrangement of the caudal mesenteric artery. Significant variability was detected in the distribution of the iliolumbar arteries about the testicular and ovaric arteries. Based on the observations and measurements carried out, some branching patterns of the aorta abdominalis are presented.

Lumbosacral Sympathetic Trunk as a Compensatory Pathway for Seminal Emission After Bilateral Hypogastric Nerve Transections in the Dog

Seminal emission after transection of canine bilateral hypogastric nerves was investigated. Stimulation of severed hypogastric nerves caused full volume seminal emission (> four drops) in all six dogs examined. In contrast, stimulation of sympathetic trunks of other six dogs at the level of caudal mesenteric artery caused no emission in three dogs and a limited volume of seminal emission (< one drop) by pressing the ampulla in the remaining. When hypogastric nerves were transected one month prior to the experiment, however, stimulation of sympathetic trunks in the same manner caused full volume of seminal emission in all six dogs. Distal dissection of sympathetic trunks demonstrated nerve fibers to the seminal tract via the pelvic splanchnic nerves. The results indicate that the seminal tract receives at least two sympathetic pathways; one from hypogastric nerves and the other from lumbosacral sympathetic trunks, and that the latter compensatorily generates seminal emission after hypogastric nerve transection.

Chronic nerve growth factor treatment of normotensive rats

The objectives of this study were to examine the effects of chronic nerve growth factor (NGF) administration on vascular innervation and blood pressure in neonatal rats. Newborn Wistar-Kyoto (WKY) rats bred from normotensive parents were chronically treated with NGF for 8 weeks. Littermate controls received saline. Sympathetic ganglia of treated animals were greatly enlarged and in the superior cervical ganglion neuronal numbers were increased 200% and nuclear areas by 46%. The catecholamine contents of several sympathetically innervated tissues were determined biochemically and found to be significantly elevated in mesenteric arteries, aorta, ileum, adrenal and salivary glands from treated compared to control animals. The catecholamine concentrations were similar to, or exceeded those of the spontaneously hypertensive rat. Histochemically, an aberrant nerve supply was evident occupying a greater volume of the adventitia of the caudal artery and mesenteric arteries. In addition, nerve fibres could be seen penetrating the vessel wall to emerge within the lumen of mesenteric blood vessels. Analysis of the smooth muscle wall of the caudal artery revealed that a small but significant hyperplastic response had been induced. Systolic blood pressures of NGF-treated and control animals were taken at one week intervals from 5 to 8 weeks of age utilizing the tail cuff method. The blood pressures of treated animals were within the normotensive range. It is concluded that chronic NGF treatment leads to changes in vascular innervation and muscle thickness that are similar to those seen in hypertensive animals. Furthermore, the results suggest the elevated levels of NGF seen in peripheral tissues of the spontaneously hypertensive rat are likely to be responsible for the hyperinnervation and resulting hyperplastic responses within vascular tissues, but not exclusively responsible for the elevated blood pressure.

Arterial vascularization of the intestine of the muskrat (Ondatra zibethicus)

SummaryThe arterial vascularization of the intestines of the muskrat (Ondatra zibethicus)This study is based on dissection of 12 adult muskrats whose arteries were injeced with latex. The main branching patterns of the cranial and caudal mesenteric arteries for the different segments of the gut are described. The position and the branching of the arteries of the muskrat are comparable to those of the laboratory rat and the American beaver. In general, the distribution patterns are reminiscent of the laboratory rat and less so of the American beaver.