Vascularization of the gastrointestinal tract of the bottlenose dolphin (Tursiops truncatus, Montagu 1821).

Odontocetes primarily rely on fish, cephalopods, and crustaceans as their main source of nutrition. In the digestive system, their polygastric complex exhibits similarities to that of their closest terrestrial relatives such as cows, sheep, and giraffes, while the entero-colic tract shares similarities with terrestrial carnivores. The morphology, caliber, and structure of the odontocete intestine are relatively constant, and, since there is no caecum, a distinction between the small and large intestine and their respective subdivisions is difficult. To address this issue, we used the intestinal vascularization pattern, specifically the course and branching of the celiac artery (CA) and the cranial and caudal mesenteric arteries (CrMA and CdMA). A series of pictures and dissections of 10 bottlenose dolphins (Tursiops truncatus) were analyzed. Additionally, we performed a cast by injecting colored polyurethane foam in both arteries and veins to measure the caliber of the arteries and clarify their monopodial or dichotomous branching. Our results showed the presence of multiple duodenal arteries (DAs) detaching from the CA. The CrMA gave origin to multiple jejunal arteries, an ileocolic artery (ICA), and, in six cases, a CdMA. In four specimens, the CdMA directly originated from the abdominal aorta. The ICA gave rise to the mesenteric ileal branches (MIB) and mesenteric anti-ileal branches and the right colic arteries (RCA) and the middle colic arteries. From the CdMA originated the left colic and cranial rectal arteries (LCA and CrRA). The measurements revealed a mixed monopodial and dichotomous branching scheme. The analysis of the arteries and their branching gave us an instrument, based on comparative anatomy, to distinguish between the different intestinal compartments. We used the midpoint of anastomoses between MIB and RCA to indicate the border between the small and the large intestine, and the midpoint of anastomoses between LCA and CrRA, to tell the colon from the rectum. This pattern suggested an elongation of the duodenum and a shortening of the colic tract that is still present in this species. These findings might be related to the crucial need to possess a long duodenal tract to digest prey ingested whole without chewing. A short aboral part is also functional to avoid gas-producing colic fermentation. The rare origin of the CdMA on the CrMA might instead be a consequence of the cranial thrust of the abdominopelvic organs related to the loss of the pelvic girdle that occurred during the evolution of cetaceans.

The distribution of the jejunal arteries in the cat.

The arterial supply of the cat jejunum was studied by gross dissection and polyurethane corrosion cast. The results showed that the jejunal arteries, which originate from the cranial mesenteric artery, varied from 5 to 15 in number. Their number was independent of the length of the cranial mesenteric artery as well as of the length of the jejunum. These arteries divided into branches giving rise to a series of orders of division from a minimum of 1 to a maximum of 7. The last orders of division terminated in a series of anastomosing arcades which resulted in a marginal artery coursing only a few millimeters from the mesenteric margin of the jejunum. This artery gave rise to straight arteries (vasa recta), whose mean number was 450 ± 60. According to their length, the vasa recta can be differentiated into short (vasa brevia) and long (vasa longa) branches. The vasa brevia ended branching into the mesenteric side of the jejunum whereas the vasa longa coursed beneath the serosa on the lateral jejunal surfaces, and reached the antimesenteric border. During their course, the vasa recta ramified and anastomosed with each other. Numerous antimesenteric anastomoses between opposing vasa longa were also observed. Based on the literature consulted, due to the large number of vasa recta (approximately one vessel per 2.9 mm of jejunal length) and the rich anastomotic network, the cat jejunum might have a better intramural distribution of blood flow and would seem less predisposed to ischemic phenomena than that of other mammals.

A complete situs inversus viscerum with hepatic, intestinal and renalvascular anomalies: one case report and review of the literatur

Situs inversus viscerum (SIV) is a rare congenital anomaly, which is still an intriguing phenomenon to anatomists and physicians alike. A complete SIV is characterized by a left-right transposition and mirror image of all thoraco-abdominal organs and their vasculature. The present report is based on one case with complete SIV, which was observed during the routine educational dissections of cadavers in the authors' Anatomy Department. A transposition of all truncal organs and their vasculature, and several variations of arteries and veins were present. The right branch of the proper hepatic artery was replaced by an artery that emanated from the superior mesenteric artery. The latter also released the inferior mesenteric artery. Additionally, a left accessory renal artery ran anterior to the inferior caval vein and posterior to the ureter to enter the hilum of the left kidney. There was also a variation in the anterior-posterior arrangement of the hilar structures of the left kidney. Additionally, a globally enlarged heart with coronary artery by-passes, a replaced aortic valve and an aortic arch aneurysm was observed. This case report is unique, as it presents a previously unreported co-incidence of SIV and hepatic, intestinal and renal vascular anomalies. It is important for the surgeon to be aware of such variations while planning an abdominal surgery in patients with SIV

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Abnormal Persistence of Embryonic Blood Supply of Liver: Anatomist's Delight, Surgeon's Nightmare.

The high incidence of hepato-biliary vascular anatomy variations necessitates its evaluation prior to performing liver transplantation, hepatobiliary, pancreatic, gastric and oesophageal surgeries. We report a unique case of persistence of embryonic arteries of the liver, wherein, the liver was supplied by five vessels. In addition to the usual right and left hepatic arteries from the hepatic artery proper, the liver received two accessory right hepatic arteries, one from the gastroduodenal artery, while another arising from superior mesenteric artery and an accessory left hepatic artery, from the left gastric artery. The origin of gastroduodenal artery was found to be unusually high and its abnormal anterior course over the common bile duct further added complexity to the hepatobiliary anatomy. The presence of these aberrant and accessory arteries predisposes to inadvertent injury leading to patient morbidity and sometimes mortality.

Tronco hepato-espleno-mesentérico: descripción de una disposición anómala del tronco celíaco / Hepato-splenic-mesenteric trunk: description of an abnormal disposition of the celiac trunk

El estudio de los patrones arteriales de distribución vascular requiere un conocimiento preciso de las variaciones anatómicas, tanto de origen y distribución de las arterias, como de sus correspondientes ramas arteriales. En este trabajo se describe la presencia de un tronco hepato-espleno-mesentérico, disposición arterial altamente infrecuente. El conocimiento de las distintas posibilidades de disposición de las arterias correspondientes al tronco celíaco y sus ramas será de importancia para la interpretación adecuada de estudios imagenológicos, como así también para la planificación precisa de actos quirúrgicos e intervencionistas en la región abdominal.

The study of arterial patterns of vascular distribution requires a precise knowledge of the anatomical variations of both origin and distribution of the corresponding arteries and arterial branches. In this work, the presence of a hepatosplenic-mesenteric trunk is described, a highly infrequent arterial disposition. The knowledge of the different possibilities of disposition of the arteries corresponding to the celiac trunk and its branches will be of importance for the adequate interpretation of imaging studies, as well as for the precise planning of surgical and interventional acts in the abdominal region.

The Na,K-ATPase-Dependent Src Kinase Signaling Changes with Mesenteric Artery Diameter.

Inhibition of the Na,K-ATPase by ouabain potentiates vascular tone and agonist-induced contraction. These effects of ouabain varies between different reports. In this study, we assessed whether the pro-contractile effect of ouabain changes with arterial diameter and the molecular mechanism behind it. Rat mesenteric small arteries of different diameters (150⁻350 µm) were studied for noradrenaline-induced changes of isometric force and intracellular Ca2+ in smooth muscle cells. These functional changes were correlated to total Src kinase and Src phosphorylation assessed immunohistochemically. High-affinity ouabain-binding sites were semi-quantified with fluorescent ouabain. We found that potentiation of noradrenaline-sensitivity by ouabain correlates positively with an increase in arterial diameter. This was not due to differences in intracellular Ca2+ responses but due to sensitization of smooth muscle cell contractile machinery to Ca2+. This was associated with ouabain-induced Src activation, which increases with increasing arterial diameter. Total Src expression was similar in arteries of different diameters but the density of high-affinity ouabain binding sites increased with increasing arterial diameters. We suggested that ouabain binding induces more Src kinase activity in mesenteric small arteries with larger diameter leading to enhanced sensitization of the contractile machinery to Ca2+.

Macroscopic anatomical study of the distribution of the cranial mesenteric artery to the intestine in the rabbit.

Intestinal surgery is commonly performed to cure bowel obstruction in rabbits, but detailed descriptions of the arterial supply to the intestine are incomplete. We investigated anatomical variations of the distribution of the cranial mesenteric artery to the intestine in 33 New Zealand White rabbits by injecting colored latex into the arteries. The cranial mesenteric artery arose independently from the abdominal aorta at about 2.0 cm caudal to the celiac artery and branched off the pancreaticoduodenal, middle colic, ileocecocolic, jejunal and ileal arteries. One or occasionally two caudal pancreaticoduodenal arteries supplied the distal duodenum, and one to three middle colic arteries supplied the transverse colon and the initial portion of the descending colon. The ileocecocolic artery arose distal to the middle colic arteries and provided the right colic, ileocecal and appendicular arteries, and branches to the proximal colon, with various branching patterns, which were grouped into four major types. These arteries and branches supplied the ileum, cecum, appendix and proximal colon. The cranial mesenteric artery also provided the jejunal arteries (predominantly 17; range 11-21) and one ileal artery supplying the jejunum and proximal ileum, respectively. The results show that the distribution patterns of the cranial mesenteric artery to the intestine in the rabbit are highly specialized to this species. Such specialization should always be considered when performing intestinal surgery in rabbits.

Hepatic arterial pattern and celiac trunk not described in literature

Knowledge of the hepatic arterial anatomy and celiac trunk is gaining importance, since the use of minimally invasive surgeries is more frequent nowadays. This kind of procedure meant that surgeons had less room for visualization of anatomical variants and work. In addition, failure to recognize the correct anatomy of the hepatic vascularization in a transplant procedure can lead to organ failure and death. The present case aims to demonstrate an arterial hepatic celiac trunk pattern that was never described by any of the acknowledged classification systems. This pattern is challenging for the surgical management of possible upper abdominal interventions, since non-recognition may lead to iatrogenesis. (AU)

Surgical pitfalls of jejunal vein anatomy in pancreaticoduodenectomy.

BACKGROUND: Pancreaticoduodenectomy (PD) is the standard surgical procedure for treating pancreatic head cancers. Considerable knowledge of proximal jejunal and pancreatic vein anatomy is a prerequisite for performing PD surgery safely, yet there appear to be no detailed descriptions of first and second jejunal vein (J1V, J2V) anatomy available in the literature. STUDY DESIGN: Adults with hepatobiliary-pancreatic disease underwent multidetector-row computed tomography with intravenous contrast (n = 155), and SYNAPSE 3D (Fujifilm Medical, Tokyo, Japan) was used to generate 3D-CT images. RESULTS: In 84% of patients, J1V and J2V formed a common trunk (FJT). There were three patterns of branches, related to the presence or absence of FJT formation and the anatomical relationships between the superior mesenteric artery (SMA) and the jejunal veins, as follows: Type 1 (n = 98, 63%) characterized by an FJT located dorsal to SMA; Type 2 (n = 32, 21%), where the FJT was located ventral to the SMA; and Type 3 (n = 25, 16%), where J1V and J2V each drained separately into the SMV. CONCLUSIONS: J1V and J2V usually formed an FJT, and separate J1V and J2V drainage into the SMV was uncommon. Preoperative information on individual patient venous anatomy would increase the safety of the PD procedure.

Vascular Structures of the Right Colon: Incidence and Variations with Their Clinical Implications.

BACKGROUND AND AIMS: There is a demand for a better understanding of the vascular structures around the right colonic area. Although right hemicolectomy with the recent concept of meticulous lymph node dissection is a standardized procedure for malignant diseases among most surgeons, variations in the actual anatomical vascular are not well understood. The aim of the present review was to present a detailed overview of the vascular variation pertinent to the surgery for right colon cancer. MATERIALS AND METHODS: Medical literature was searched for the articles highlighting the vascular variation relevant to the right colon cancer surgery. RESULTS: Recently, there have been many detailed studies on applied surgical vascular anatomy based on cadaveric dissections, as well as radiological and intraoperative examinations to overcome misconceptions concerning the arterial supply and venous drainage to the right colon. Ileocolic artery and middle colic artery are consistently present in all patients arising from the superior mesenteric artery. Even though the ileocolic artery passes posterior to the superior mesenteric vein in most of the cases, in some cases courses anterior to the superior mesenteric artery. The right colic artery is inconsistently present ranging from 63% to 10% across different studies. Ileocolic vein and middle colic vein is always present, while the right colic vein is absent in 50% of patients. The gastrocolic trunk of Henle is present in 46%-100% patients across many studies with variation in the tributaries ranging from bipodal to tetrapodal. Commonly, it is found that the right colonic veins, including the right colic vein, middle colic vein, and superior right colic vein, share the confluence forming the gastrocolic trunk of Henle in a highly variable frequency and different forms. CONCLUSION: Understanding the incidence and variations of the vascular anatomy of right side colon is of crucial importance. Failure to recognize the variation during surgery can result in troublesome bleeding especially during minimal invasive surgery.

The distribution and adipogenic potential of perivascular adipose tissue adipocyte progenitors is dependent on sexual dimorphism and vessel location.

There are sex associated differences in the risk for cardiovascular comorbidities in obesity and metabolic syndrome. A common clinical finding in these diseases is the expansion of perivascular adipose tissues (PVAT) which is associated with alterations in their role as regulators of vessel function. PVAT hyperplasia and hypertrophy are dependent on the biology of populations of adipocyte progenitor cells (APC). It is currently unclear if PVAT enlargement diverges between males and females and the mechanisms linking APC biology with sexual dimorphism remain poorly understood. This study tested the hypothesis that vessel location and sexual dimorphism affect the distribution and adipogenic capacity of APC in cardiovascular disease risk relevant PVAT sites. PVAT from thoracic aorta (aPVAT) and mesenteric resistance arteries (mPVAT) was collected from 10-week-old female and male Sprague-Dawley rats. Differences in APC distribution in stromal vascular fraction cells from PVAT were determined. APC were defined as cells expressing CD34, CD44, and platelet derived growth factor α In both sexes aPVAT had fewer APC compared to mPVAT and perigonadal adipose tissue (GON). Sex-related differences were observed in the expression of CD34, where females had fewer CD34+ cells in PVATs. APC proliferation and adipogenic capacity in vitro were not affected by sex. However, APC from aPVAT had a lower proliferation capacity compared to mPVAT These data demonstrate that the distribution of APC within PVAT exhibits sexual dimorphism and is affected by anatomical location.

Origem e principais ramificações das artérias mesentéricas cranial e caudal em avestruz (Struthio camelus Linnaeus, 1758) / Origin and main ramifications of the cranial and caudal mesenteric arteries in ostrich (Struthio camelus Linnaeus, 1758)

As artérias mesentéricas das aves são importantes para a irrigação do aparelho digestório e encontram-se associadas ao ganho de peso e conversão alimentar. Objetivou-se descrever as origens, esqueletopias, medidas e principais ramificações das artérias mesentéricas cranial e caudal em avestruzes. Foram utilizados 41 cadáveres de filhotes de avestruzes, 23 machos e 18 fêmeas, obtidos de um criadouro após morte natural. Os cadáveres foram fixados com formaldeído a 10% e tiveram o sistema vascular preenchido com Petrolatex® S-65 colorido. As artérias mesentéricas, cranial e caudal e seus ramos proximais foram dissecados "in situ" e medidas com paquímetro digital. A artéria mesentérica cranial teve comprimento médio de 3,68 ± 1,04 cm e surgiu da aorta descendente ao nível da oitava vértebra torácica na maioria dos casos. Ramificou-se em artérias jejunal e ileocecal. A artéria jejunal ofereceu média de 14,04 ±2,08 ramos ao jejuno e a artéria ileocecal originou um ramo retal e outro que se bifurcou para derivar ramos para íleo, ceco e reto. Em um espécime macho a artéria ileocecal foi ramo da artéria celíaca. A artéria mesentérica caudal originou-se na porção terminal da aorta descendente predominantemente ao nível das 4ª e 6ª vértebras sacro-caudais. Perto da extremidade caudal do rim emitiu os ramos cranial e caudal. O primeiro irrigou o reto e anastomosou-se com ramo retal da artéria mesentérica cranial; o segundo irrigou a porção final do reto, cloaca e bolsa cloacal. Não houve diferença significativa (p<0,05) entre as medidas, esqueletopia e número de ramificações das artérias entre os sexos.(AU)

The mesenteric arteries of birds are important for the irrigation of the digestive tract and are associated with weight gain and food conversion. This study aimed to describe the origins, skeletopy, measures and main branches of cranial and caudal mesenteric arteries in ostriches. Forty-one cadavers of ostrich chicks, 23 males and 18 females, obtained from a farmer after natural death. The cadavers were fixed with 10% formaldehyde solution and their vascular system was filled with colored Petrolatex® S-65. The cranial and caudal mesenteric arteries and its proximal branches were dissected in situ and measured with a digital caliper. The mesenteric artery had an average length of 3.68cm±1.04 and emerged from the descending aorta at the level of the eighth thoracic vertebra in most cases; it branched into jejunal and ileocecal arteries. The jejunal artery sent a mean of 14 (14.04±2.08) branches to the jejunum. The ileocecal artery sent a rectal branch and another branch that irrigated ileum, cecum and rectum. In a male specimen the ileocecal artery was originated from the celiac artery. The caudal mesenteric artery emerged in the terminal portion of the descending aorta predominantly at the level of the 4th and 6th sacrocaudal vertebrae. Near the caudal end of the kidney it issued the cranial and caudal branches. The first irrigated the rectum and anastomosed with the rectal branch of the cranial mesenteric artery; the second irrigated the final part of the rectum, cloaca and cloacal bursa. There was no significant difference (p<0.05) between measurements, skeletopy and number of branches of the arteries between genders.(AU)

The right colic artery: An anatomical demonstration and its relevance in the laparoscopic era.

INTRODUCTION Hemicolectomies are not tailored in right-sided colon cancer resections, despite significant variation in the incidence and origin of the right colic artery (RCA). Early evidence suggests that removal of the relevant lymphovascular package and associated cancer as part of complete mesocolic excision (CME), rather than the entire right colon, may produce better outcomes. Advancing laparoscopic techniques are making this possible, and so it is increasingly important to more precisely define the anatomy of the RCA. METHODS To demonstrate the incidence and variation of the RCA, 25 formalin embalmed cadavers were dissected. Consent to dissection and photography was obtained under Human Tissue Act regulations. RESULTS Eleven female and 14 male cadavers (mean age 79.7 years, range 41-95 years) were included. The RCA originated from the right branch of the middle colic artery in nine cadavers (36%), while it arose from the superior mesenteric artery in eight cases (32%) and from the ileocolic or root of the middle colic artery in a smaller number of specimens. The RCA was absent in two individuals. CONCLUSIONS The RCA arises from the right branch of the middle colic artery in a considerable number of cases. The literature to date does not reflect the precision of anatomical understanding required for CME; hence, a new definition for the right colic vessel is proposed.

Solución del caso 12. Arteria renal derecha con origen aberrante / Solution to case 12. Aberrant origin in a right renal artery

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Functional Expression Profile of Voltage-Gated K(+) Channel Subunits in Rat Small Mesenteric Arteries.

Multiple K v channel complexes contribute to total K v current in numerous cell types and usually subserve different physiological functions. Identifying the complete compliment of functional K v channel subunits in cells is a prerequisite to understanding regulatory function. It was the goal of this work to determine the complete K v subunit compliment that contribute to functional K v currents in rat small mesenteric artery (SMA) myocytes as a prelude to studying channel regulation. Using RNA prepared from freshly dispersed myocytes, high levels of K v 1.2, 1.5, and 2.1 and lower levels of K v 7.4 α-subunit expressions were demonstrated by quantitative PCR and confirmed by Western blotting. Selective inhibitors correolide (K v 1; COR), stromatoxin (K v 2.1; ScTx), and linopirdine (K v 7.4; LINO) decreased K v current at +40 mV in SMA by 46 ± 4, 48 ± 4, and 6.5 ± 2 %, respectively, and K v current in SMA was insensitive to α-dendrotoxin. Contractions of SMA segments pretreated with 100 nmol/L phenylephrine were enhanced by 27 ± 3, 30 ± 8, and 7 ± 3 % of the response to 120 mmol/L KCl by COR, ScTX, and LINO, respectively. The presence of K v 6.1, 9.3, ß1.1, and ß1.2 was demonstrated by RT-PCR using myocyte RNA with expressions of K vß1.2 and K v 9.3 about tenfold higher than K vß1.1 and K v 6.1, respectively. Selective inhibitors of K v 1.3, 3.4, 4.1, and 4.3 channels also found at the RNA and/or protein level had no significant effect on K v current or contraction. These results suggest that K v current in rat SMA myocytes are dominated equally by two major components consisting of K v 1.2-1.5-ß1.2 and K v 2.1-9.3 channels along with a smaller contribution from K v 7.4 channels but differences in voltage dependence of activation allows all three to provide significant contributions to SMA function at physiological voltages.

Anatomy of the transverse colon revisited with respect to complete mesocolic excision and possible pathways of aberrant lymphatic tumor spread.

PURPOSE: Although lymph node metastases to pancreatic and gastroepiploic lymph node stations in transverse colon cancer have been described, the mode of lymphatic spread in this area remains unclear. This study was undertaken to describe possible pathways of aberrant lymphatic spread in the complex anatomic area of the proximal superior mesenteric artery and vein, the greater omentum, and the lower pancreatic border. METHODS: Abdominal specimens obtained from four cadaveric donors were dissected according to the principles of complete mesocolic excision. The vascular architecture of the transverse colon was scrutinized in search of possible pathways of lymphatic spread to the pancreatic and gastroepiploic lymph nodes. RESULTS: Vascular connections between the transverse colon and the greater omentum at the level of both the hepatic and the splenic flexures could be identified. In addition, small vessels running from the transverse mesocolon to the lower pancreatic border in the area between the middle colic artery and the inferior mesenteric vein were demonstrated. Moreover, venous tributaries to the gastrocolic trunk could be exposed to highlight its surgical importance as a guiding structure for complete mesocolic excision. CONCLUSION: The technical feasibility to clearly separate embryologic compartments by predefined tissue planes in complete mesocolic excision was confirmed. However, the vicinity of all three endodermal intestinal segments (foregut, midgut, and hindgut) obviously gives way to vascular connections that might serve as potential pathways for lymphatic metastatic spread of transverse colon cancer.

Arterial Vascularization of the Gastrointestinal Tract of the Pampas Deer (Ozotoceros bezoarticus, Linnaeus, 1758).

Based on gross dissection of fifteen adult animals (11 females, 4 males), we described the arterial supply of the stomach and intestines of the pampas deer (Ozotoceros bezoarticus), a South American endangered species. The coeliac artery emitted the splenic, left gastric and hepatic arteries. The splenic artery directed towards the spleen, and the right ruminal artery, which is its only collateral directed towards the stomach, being the main artery of the rumen. The left gastric artery gave origin to the left ruminal, the reticular and the left gastroepiploic arteries. The left gastroepiploic artery originated the reticular accessory artery. Both arteries, gastric and left gastroepiploic, anastomosed their right counterparts derived from the hepatic artery on the curvatures of the abomasum. The cranial mesenteric artery irrigated the second half of the duodenum until the beginning of the descending colon. The thickest branch emitted by the cranial mesenteric artery was the ileocolic artery, which was destined to the ascending colon, caecum and ileum. The colic branches and the right colic arteries were irradiated on the right surface of the spiral loop of the ascending colon and distributed to both centripetal and centrifugal coils of the ascending colon; the colic branches were also anastomosed with the last jejunals and ileals and with the right colic arteries. There were no variations in the origin of any of the main branches derived from the coeliac and cranial mesenteric arteries. This species had a basic pattern of arterial distribution similar to small domestic ruminants.

A mixed-type intermesenteric trunk as a major contributor to the ascending, transverse, and descending colons: a case report.

PURPOSE: We present a case in which a mixed-type intermesenteric trunk was the major arterial supply for the ascending, transverse, and descending colons. METHODS: We dissected a cadaver of a man aged 74 years that was used for a routine abdominal dissection course of 2nd year medical students. RESULTS: We observed that a mixed-type intermesenteric trunk supplied the majority of the colon, originating from the inferior mesenteric artery. The vessel was non-tortuous and had a counter clockwise course. It gave branches that supply the marginal artery at the splenic and hepatic flexures and at the transverse colon and finally it anastomosed with the ileocolic artery at the ileocecal junction. Through the intermesenteric trunk, the inferior mesenteric artery supplied the descending, transverse, and ascending colons with contributions from the sigmoidal and ileocolic arteries. CONCLUSIONS: The intermesenteric trunk is an important central connection between the superior and inferior mesenteric arteries. It probably is an embryologic remnant that constituted a longitudinal anastomosis between both mesenteric arteries.

Surgical Anatomical Landmarks of the Thoracolumbar Vertebral Column on Magnetic Resonance Imaging in Dogs.

Magnetic resonance imaging (MRI) in veterinary medicine profoundly improved spinal cord disease investigation in canine patients. We aimed to further describe the anatomical landmarks of the thoracolumbar junction in sagittal MRI sequences. MRI studies from 90 dogs were reviewed retrospectively, representing a broad cross section of breeds and body weights. The ratio of the distance from the dorsal aspect of the vertebral canal to the dorsal aspect of the transverse process or rib articulation relative to the length of L2 vertebra was determined for T12, T13, L1 and L2 vertebrae. A statistically significant difference was noted with the transverse processes being more ventrally located than the cranial fovea costalis. The lumbar transverse processes and rib articulations dramatically varied in shape, being oval or round, respectively. The sagittal image at the level of the lateral margin of the articular facet joint proved to be the most consistent for review of these structures.

Assessing Myogenic Response and Vasoactivity In Resistance Mesenteric Arteries Using Pressure Myography.

Small resistance arteries constrict and dilate respectively in response to increased or decreased intraluminal pressure; this phenomenon known as myogenic response is a key regulator of local blood flow. In isobaric conditions small resistance arteries develop sustained constriction known as myogenic tone (MT), which is a major determinant of systemic vascular resistance (SVR). Hence, ex vivo pressurized preparations of small resistance arteries are major tools to study microvascular function in near-physiological states. To achieve this, a freshly isolated intact segment of a small resistance artery (diameter ~260 µm) is mounted onto two small glass cannulas and pressurized. These arterial preparations retain most in vivo characteristics and permit assessment of vascular tone in real-time. Here we provide a detailed protocol for assessing vasoactivity in pressurized small resistance mesenteric arteries from rats; these arteries develop sustained vasoconstriction - approximately 25% of maximal diameter - when pressurized at 70 mmHg. These arterial preparations may be used to study the effect of investigational compounds on relationship between intra-arterial pressure and vasoactivity and determine changes in microvascular function in animal models of various diseases.