Caudal Cerebral Artery Research Articles

Comprehensive analysis of the rostral and caudal cerebral artery branching patterns in the dromedary camel (Camelus dromedarius).

In mammals, the cerebral cortex depends on a robust blood supply for optimal function. The rostral and caudal cerebral arteries are critical for supplying the cerebrum. This study presents the first detailed anatomical description of the rostral and caudal cerebral arteries of dromedary camels (Camelus dromedarius), including their origins, routes, and complex branching patterns. A sample of 55 heads from male dromedary camels aged 2-6 years was analyzed using advanced casting techniques with various casting materials to provide precise visualization of these arterial structures. The rostral cerebral arteries originate dorsally from the rostral epidural rete mirabile (RERM), while the caudal cerebral arteries arise from the caudal communicating artery, which is another branch of the RERM. Both sets of arteries give rise to multiple cortical branches responsible for supplying the medial aspects of the frontal, parietal, and temporal lobes, as well as the medial and caudal regions of the occipital lobes. This study significantly expands our understanding of the cerebrovascular anatomy of dromedary camels. Our findings have potential implications for veterinary medicine in the diagnosis and treatment of neurological disorders in camels and may offer insights into broader comparative neuroscience research.

Neurovascular description in the South American plains vizcacha, Lagostomus maximus (Chinchilloidea, Caviomorpha). A study involving evolutionarily related species of Caviomorpha and Muroidea.

Oxygenated blood is required for the adequate metabolic activity of the brain. This is supplied by the circle of Willis (CoW) and the vertebrobasilar and carotid systems. The CoW ensures blood flow in case of arterial stenosis or occlusion. Different animal models have been explored for the CoW morphological and functional study. This work aims to characterize the vascular architecture of the CoW of the plains vizcacha, Lagostomus maximus (Suborder: Hystricomorpha), and to compare it with evolutionarily related species of Caviomorpha and Muroidea. The blood supply in adult plains vizcachas was studied using latex cerebrovascular casts and angiography. A caudo-rostral flow direction was determined, beginning in the spinal and vertebral arteries and converging in the basilar artery which bifurcates in the carotid-basilar communication in the caudal communicating arteries. In the first third of its course, the caudal cerebral arteries project laterally, and the middle and rostral cerebral arteries bifurcate from their rostral terminal segment, supplying the temporo-parietal and frontal cortex. The CoW architecture is mainly conserved between rodent species. Likewise, the small neurovascular variations observed could be considered phylogenetic morphological variations more than evolutionary adaptations. The absence of the rostral communicating artery that generates the rostral open architecture of the CoW in the vizcacha as in the other analyzed species, supports the need for a revision of the CoW classical function as a security system. Finally, this work supports the importance of expanding our understanding of brain anatomy among species, which may contribute to a better understanding of functional neuroanatomy.

A comprehensive study on the arterial vasculature of the brain in water buffalo (Bubalus bubalis): Clinical correlates.

The present study was designed to provide a comprehensive analysis of the anatomical aspects of arterial blood vasculature in the water buffalo brains. Fifty cranial cavities of adult water buffaloes were opened via both the dorsal and ventral approaches and the arteries were exposed and photographed. The buffalo rostral epidural rete mirabile generally resembled that of large ruminants. The oculomotor, abducent and trigeminal nerves were intimately associated with the rostral rete. Similar to the majority of ruminants, the arterial circle of the brain was heart-shaped in buffalos and presented all collateral blood vessels as mentioned in the previous literature. The study further revealed that the cranial nerve roots were closely related to the arterial circle of the brain and could be used as indicators for differentiating various branches of the arterial circle of the brain. In addition to the usual variations of the arterial circle of the brain, a bihemispheric rostral cerebral artery along with an aplastic rostral cerebral artery were reported for the first time. The deviant behaviour of the rostral cerebral artery forms a baseline to study various clinical conditions of the blood vasculature in the buffalo brain. The rostral choroidal, middle cerebral and the caudal cerebral arteries constantly were emerged as single vessels without any variations. In conclusion, the anatomy of the arterial vasculature of the buffalo brain observed in the present study provided evidence of its morphological resemblance to other species of the Bovini tribe.

Comparison of bone subtraction CT angiography with standard CT angiography for evaluating circle of Willis in normal dogs.

Bone subtraction computed tomography angiography (BSCTA) is a useful alternative technique for improving visualization of vessels surrounded by skull bone. However, no studies have compared computed tomography angiography (CTA) and BSCTA for improving the visibility of canine cerebral blood vessels. To evaluate the potential benefit of BSCTA for better delineation of brain arteries of the circle of Willis (CoW) in dogs by comparing BSCTA with non-subtraction computed tomography angiography (NSCTA). Brain CTA was performed for nine healthy beagle dogs using a bolus tracking method with saline flushing. A total dose of 600 mgI/kg of contrast agent with an iodine content of 370 mgI/mL was injected at a rate of 4 ml/s. Bone removal was achieved automatically by subtracting non-enhanced computed tomography (CT) data from contrast CT data. Five main intracranial arteries of the CoW were analyzed and graded on a scale of five for qualitative evaluation. Scores of basilar artery, middle cerebral artery, and rostral cerebral artery in the BSCTA group were significantly higher than those in the NSCTA group (p = 0.001, p = 0.020, and p < 0.0001, respectively). Scores of rostral cerebellar artery (RcA) and caudal cerebral artery (CCA) did not differ significantly between the two groups. However, scores of RcA and CCA in the BSCTA group were higher than those in the NSCTA group. BSCTA improved visualization of intracranial arteries of the CoW with close contact to bone. Thus, it should be recommended as a routine scan method in dogs suspected of having brain vessel disease.

Optimal placement of the region of interest for bolus tracking on brain computed tomography angiography in Beagle dogs.

This study aimed to determine the optimal placement of the region of interest (ROI) among four anatomical sites—pulmonary artery (PA), pulmonary vein (PV), aortic arch (AA), and carotid artery (CA)—in computed tomography (CT) brain angiography with automatic bolus tracking in healthy beagle dogs. Six beagles were included, and CT brain angiography was performed four times for each dog, to cover each ROI. The scan parameters, amount, and injection rate of the contrast medium were the same. The major intracranial arteries were selected for quantitative and qualitative evaluation: caudal cerebellar artery (CcA), basilar artery (BA), rostral cerebellar artery (RcA), caudal cerebral artery (CCA), middle cerebral artery (MCA), and rostral cerebral artery (RCA). Quantitative evaluation showed significantly higher CT attenuation values for the RcA, CCA, and MCA in the PA group and RcA and MCA in the PV group than in the CA group. Qualitative analysis revealed significantly higher scores for the BA, CCA, and MCA in the PA and PV groups than in the CA group. Venous contamination did not differ significantly among the ROIs, but the mean scores of the AA and CA groups were higher than those of the PA and PV groups. CT brain angiography using bolus tracking in the beagle dogs showed that the ROI should be placed at the PA or PV rather than at the CA for optimal images with strong contrast enhancement of the BA, RcA, CCA, and MCA and minimal venous contamination.

Systematization, distribution, and territories of the caudal cerebral artery on the surface of the brain in nutria (Myocastor coypus)

ABSTRACT: The nutria (Myocastor coypus) is a medium-sized, semi-aquatic rodent valued by the skin and meat industry. This study aimed to describe and systematize the caudal cerebral artery on the brain surface in nutria, establishing a standard model and its main variations in this species. The thirty animals used were euthanized according to animal welfare rules. The vessels were filled with latex stained with red pigment and the samples were fixed in formaldehyde. In nutria, the brain was vascularized by the vertebral basilar system. The terminal branches of the basilar artery originated the rostral cerebellar, caudal cerebral, rostral choroidal and middle cerebral arteries, and its terminal branch, the rostral cerebral artery. The terminal branch of the basilar artery projected the caudal cerebral artery, which is usually a single medium-caliber vessel, into the transverse fissure of the brain. The caudal cerebral artery was presented as a single (66.7% of the cases to the right and 76.7% to the left) and double vessel (33.3% of the cases to the right and 23.3% to the left). It originated the rostral mesencephalic artery, the proximal component, and the caudal inter-hemispheric artery. The terminal branches of the rostral and caudal tectal mesencephalic arteries formed a typical anastomotic network. The caudal inter-hemispheric artery emitted central branches, the caudal choroidal artery, hemispherical occipital arteries, rostral tectal mesencephalic branches and distal components, and anastomosed “in osculum” with the terminal branches of the rostral inter-hemispheric artery. The caudal choroidal artery anastomosed with the rostral choroidal artery, where it branched out on the thalamic mass, vascularizing all diencephalic structures and the hippocampus. The caudal cerebral artery and its terminal branches anastomosed with the terminal branches of the rostral and middle cerebral arteries in a restricted region of the caudal pole of the cerebral hemisphere. The vascularization area of the caudal cerebral artery and its central branches in the paleopallial of the piriform lobe is extremely restricted, caudomedially.

Vascularization of the Alouatta belzebul brain base

ABSTRACT: We studied the arterial circle in the brain of five specimens of the Alouatta belzebul primate. The material had the arterial system perfused (water at 40°C), injected with stained latex (Neoprene 650), fixed in aqueous formaldehyde solution (10%) and dissected for vessel verification. The arterial circle of this primate is composed of two vascular systems: the vertebra-basilar and the carotid ones, which anastomose to close the arterial circuit. In the caudal portion of the arterial circle, there are the vertebral arteries and their branches: the rostral spinal artery and the caudal inferior cerebellar artery. The anastomosis of the vertebral arteries gives rise to the basilar artery. It presented an anatomical variation at the beginning of its path, forming a double basilar artery, called arterial island. In its course, it emitted branches giving rise to the rostral inferior cerebellar artery, the pontine arteries, the rostral cerebellar arteries, the satellite rostral cerebellar arteries and its terminal branch, the caudal cerebral artery, which presented itself in two segments: the pre-communicating one and post-communicating, joining the internal carotid artery and originating the caudal communicating artery. This group of arteries and anastomoses enclose the caudal portion of the arterial circle. From the right and left internal carotid arteries begins the rostral portion of the arterial circle, which consists of the right and left rostral cerebral arteries and the right and left middle cerebral arteries. The rostral cerebral arteries anastomose into a single trunk, giving rise to the interhemispheric artery, and in A. belzebul and Sapajus libidinosus, the rostral communicating artery is absent. The interhemispheric artery goes to the midbrain region and the corpus callosum knee divides into pericalous artery and callosarginal artery, which will supply the pre and post-central regions of the cerebral hemispheres of this species, as well as other non-human and human primates. It is noted that in the first part of the left rostral cerebral artery, there is a direct inosculation between the recurrent branch of the rostral cerebral artery and left middle cerebral artery to supply the entorhinal region. This fact also occurs in Pongo spp. The middle cerebral artery travels along the lateral sulcus where it emits several superficial branches to irrigate the superior and inferior lateral cortical regions of the frontal, parietal and temporal lobes. It is not part of the arterial circle but is the terminal branch of the internal carotid artery. A. belzebul can be considered to depend on two sources of supply to the brain: the vertebra-basilar and carotid systems, contributing to the intervention of veterinarians during clinical and surgical procedures in other primates, as well as the preservation of wild animals.

Systematization and Description of Arterial Vascularization of the Paleopallia Area on the Brain Surface of Chinchilla (Chinchilla lanigera)

Background: Chinchilla (Chinchilla lanigera) is a small rodent that in recent years has been increasingly used as a laboratory animal by different researchers. Brain irrigation is the object of study by several authors, being chinchilla classified as a vertebrobasillary animal, that is, it does not depend on the internal carotid artery to originate its cerebral arterial vascularization. Thus, the objective of this study was to systematize and describe the branches of the rostral, middle and caudal cerebral arteries that vascularized the paleopallia area of the chinchilla. Materials, Methods &amp; Results: Thirty Chinchilla lanigera brains were used in this study, 17 females and 13 adult males from farms in the municipalities of Viamão and Santa Maria in the state of Rio Grande do Sul, Brazil. The animals were heparinized, with 5000 IU / animal, and after 30 min were sacrificed with 8 mL / 2.5% sodium thiopental animal, both intraperitoneally. The thoracic cavity was opened, the cardiac apex sectioned and the aortic arch was cannulated through the left ventricle. The arterial system was flushed with 0.9% cooled saline, 100mL / animal and then filled with 603 latex stained red with specific dye. The skin was recessed and a bone window opened in the cranial vault. Thus the pieces were fixed in 20% formaldehyde for seven days and after this period, the brain with a cervical spinal cord segment was removed and ventral schematic drawings of all preparations were prepared. The Veterinary Anatomical Nomina (2017) was used to name the cerebral arteries and their branches and for the statistical analysis of the results, the percentage calculation was applied. Brain irrigation in the chinchilla was supplied by the basilar artery, which was formed by anastomosis of the terminal branches of the right and left vertebral arteries, in the most caudal portion of the oblong medulla. The paleopallia areas corresponded to the olfactory trine, lateral brain fossa, piriform lobe, bulb and olfactory peduncle, and the medial and lateral olfactory tracts. Irrigation of the chinchilla paleopallia area was supplied by central branches from the caudal, middle and rostral cerebral arteries, and by the central branches originating from the terminal branches of the basilar artery.Discussion: Justifying the discussion about the systematization and description of arterial vascularization of the paleopallia area of the chinchilla brain, it was compared to other species such as wild boar, nutria, rabbit and greasy of the field, because only in these animals were found references on the subject. . The central branches of the cerebral arteries were mainly responsible for the irrigation of the paleopallia areas of the chinchilla brain, as well as in the species already mentioned. Due to the variation of the types of arterial vascularization in each of these species, small differences were observed, and these central vessels may also be emitted from the rostral branch of the internal carotid artery, such as in the rabbit and fatty grapefruit, or from the brain carotid artery as in wildboar. Similarities between chinchilla and nutria were also observed, and these central branches may originate from the terminal branches of the basilar artery in both species.

Systematization and Description of the Arterial Blood Supply of the Paleopallia areas in the Brain Surface of the Wild Boar (Sus scrofa scrofa)

Background: The study was performed on wild boar (Sus scrofa scrofa) wich is a wild ancestor of the domestic pig and is not part of Brazilian fauna. The arterial blood supply of the encephalus has been studied by some researchers, who have systematized the cerebral blood supply from the rostral and caudal epidural rete mirabile and its sources in wild boar until the blood supply of the base of the brain. The objective was to improve the understanding of the arterial blood supply of the brain, particularly the paleopallium, of the wild boar and to provide a reference for comparative anatomy studies. Materials, Methods &amp; Results: A total of 30 brains were obtained from an officially authorised slaughterhouse and approved by Brazilian Institute of Environment and Natural Renowable Resources. The animals were desensitized, followed by bleending of the jugular veins and common carotid arteries near the entrance of the thorax, according to the slaughter procedure. Finally, the animals were decapitated at the level of axis vertebra. The cerebral arterial system of each animal was rinsed (cooled saline containing 2500 IU of heparin) and drained by the jugular veins, and vessels were filled with latex 603 stained with specific red dye. The heads were submerged for one hour in running water immersed in 20% formaldehyde for fixation; the brains were removed along with a cervical segment of the spinal cord. The duramater was removed, and the arteries were dissected. Schematic drawings of the ventral view of the all preparations were made using magnifying glasses and photographic records. The Nomina Anatomica Veterinaria was used to named the cerebral arteries and their branches, and calculation of pecentages was applied in the statistical analysis. The cerebral carotid artery originating from the rostral epidural rete mirabile emitted a rostral branch and a caudal branch on the side of the hypophysis gland. The rostral branch emitted one to three middle cerebral arteries and continued as rostral cerebral artery. The latter emitted the superficial and perforating central arteries, lateral rhinal artery, ethmoidal artery, medial branch and medial rhinal artery. Discussion: Wild boar is a macrosmatic animal, it presents well-developed areas of the paleopallium that are exclusively olfactory. Its extensive paleopallium was nourished by branches of the rostral cerebral artery and its collateral branches, including the lateral rhinal, ethmoidal, and medial branch and the medial rhinal artery. The rostral cerebral arteries and their collateral branches supplied blood to the olfactory bulb, olfactory peduncle, two-thirds of the lateral olfactory tract, medial olfactory tract, and rostral two-thirds of the olfactory trigone. The medial cerebral arteries within the lateral fossa of the brain, emitted superficial rostral central branches to the paleopallium, perforating central branches (striated) to the lateral fossa of the brain and caudal third of the olfactory trigone and caudal central branches to the piriform lobe. The rostral most two-thirds of a small medial band of the piriform lobe was vascularised by central branches originating mainly from the rostral branch of the cerebral cartotid artery. The paleopallium in the wild boar was nourished by branches of the cerebral rostral, middle and caudal arteries and by the central branches of the cerebral carotid artery. The arterial blood supply of the paleopallium in the wild boar was compared to the chinchilla, nutria, rabbit and pampas fox. Three cerebral vessels were mainly responsable for the emission of the central branches that supplied blood to the paleopallium, namely the middle, rostral, and caudal cerebral arteries. The differences or variations among these species were due to the type of cerebral blood supply in the formation of the cerebral arterial circle.Keywords : anatomy, brain, paleopallia, arteries, Artiodactila, wild boar.

The Eurasian Elk's (Alces alces) Brain Base Arteries in View of Vascular Variation.

This article presents the results of analysis of the arterial vascular region of the Eurasian elk, which is a representative of the Cervidae family. The study was conducted on 39 Eurasian elks. The head arteries of 25 animals were filled with LBS 3040 synthetic latex. The head arteries of the other 14 Eurasian elks were filled with an acetone solution of stained chlorinated polyvinyl chloride and macerated. The arterial circle of the Eurasian elk's brain is composed of bilateral rostral cerebral arteries and caudal communicating arteries. The basilar artery closes the arterial circle caudally. The rostral cerebral artery first ramifies into the rostral choroidal artery, then, the middle cerebral artery and the rostral communicating artery. The caudal cerebral artery and the rostral cerebellar artery branch off the caudal communicating artery. The arterial pattern of the Eurasian elk's brain base is similar to the arteries found in other deer. Like in other Ruminantia, the rostral epidural rete mirabile is a unique structure in the Eurasian elk's arterial system. Anat Rec, 302:339-345, 2019. © 2018 Wiley Periodicals, Inc.

Gross Anatomy and Vascularization of the Brain of Pacarana (Dinomys branickii)

Background: The pacarana lives in South America and has herbivorous and nocturnal habits. It is a rare species with scarce data concerning its morphology and adding more data is important in establishing its vulnerability. The aim was to describe its macroscopic brain anatomy, as well as the brain vascularization.Materials, Methods &amp; Results: Two specimens were available for this study, that were donated post-mortem. The animals were injected with latex and fixed with 10% formaldehyde. Upon exposure and removal of the brain its main features were described. The rhinal fissure is single and the lateral sulcus arises from its caudal part. There are two sagittal sulci, an extensive medial sulcus and a short lateral sulcus. The piriform lobe is vermiform and the rostral part is smaller. The caudal colliculus is larger than the rostral colliculus and they are separated by a sulcus. The cerebellum has oval shape and the flocculus lobe is not conspicuous. The cerebral arterial circle was analyzed and described. The brain is supplied by the vertebrobasilar system only. The cerebral arterial circle is formed by the terminal branch of the basilar artery, the caudal communicating artery, the rostral cerebral artery and the rostral communicating artery. The caudal and middle cerebellar arteries are branches of the basilar artery. The terminal branch of the basilar artery originates the rostral cerebellar artery and the caudal cerebral artery. From the end of the caudal communicating artery and the beginning of the rostral cerebral artery arises the middle cerebral artery.Discussion: The cerebral structures related to sensory inputs reflect the species usage of senses, or rather one is intrinsically correlated to the other. The caudal colliculus is larger than the rostral colliculus, as the former is related to hearing and the latter to the vision, this indicates that the visual sense is not so important. Indeed, the animals are nocturnal and have small eyes. The hearing on the other hand is used in social interactions, to indicate combat, threat and defensive situations, for example. The rhinencephalon has the most conspicuous external sensory structures and the animals use olfaction for social behaviors, even producing a gland exudate to mark territory. Most brain features are similar with other species in the infraorder Caviomorpha. The brain of the pacarana resembles the brains of the Patagonian mara, capybara and guinea pig. The common porcupine presents a different shape to the brain. The guinea pig and the common porcupine are lissencephalic. The animals that present sulci in the brain, follow this order from more to less girencephalic: capybara, mara and pacarana. The rhinal fissure is important because it delimits the rhinencephalon and it is present in all the animals mentioned above. In the mara, the colliculi are exposed in dorsal and lateral views, however, this does not happen for the pacarana. The cerebellum is similar in these species, but the flocculus is more pronounced in the guinea pig. The brain of Caviomorpha species is supplied only by the vertebrobasilar system in most species analyzed, as in the capybara, guinea pig, coypus, mara, chinchilla, degu and in pacarana, where the absence of the carotid artery was observed. In some species the rostral cerebral artery anastomosis in a single branch that runs towards the corpus callosum (degu, capybara, chinchilla and coypus), but in the pacarana the rostral cerebral artery is present in both left and right sides, then branching towards the corpus callosum and the splenial sulcus. In summary, the pacarana presents brain features similar to other Caviomorpha, with some specific species variation.

Systematization of the Brain Base Arteries in Nutria (Myocastor coypus)

Background: The nutria (Myocastor coypus) is a medium-size, semi-aquatic rodent, valued in skin and meat industry. The brain circulation has been well studied in rodents but not in nutria. To understand and compare the phylogenetic development of the arteries of the base of the brain in rodents, this paper aims to describe and systematize these arteries, establishing a standard model and its main variations in nutria.Materials, Methods &amp; Results: Following approval by the Ethics Committee of Federal University of Rio Grande do Sul, thirty nutrias from a commercial establishment authorized by Brazilian Institute of Environment and Natural Resources (IBAMA) were studied. For euthanasia, was applied heparin (10000 U.I for animal), intraperitoneally, and after thirty minutes the animals ware sedated with acepromazine (0.5 mg/kg) and meperidine (20 mg/kg), intramuscularly. After sedation, they were euthanized with thiopental sodium (120 mg/kg) and lidocaine (10 mg/mL), intraperitoneally. The heart was accessed, the cardiac apex was sectioned, the aorta was cannulated via the left ventricle and clamped close to the diaphragm, and the arterial system was washed with saline solution and filled with latex. The animals were submerged in water for latex polymerization, the trunk was sectioned, the skin removed and a bony window was opened in the skull vault. The pieces were fixed in formaldehyde. The brains were removed, and schematic drawings of the arteries from the base of the brain were made for elaboration of the results. The nutria’s brain was vascularized by the vertebro-basilar system. The terminal branches of the right and left vertebral artery were anastomosed on the ventral surface of the medulla oblongata, forming the basilar artery, and caudally the ventral spinal artery. The basilar artery formed collateral branches, the caudal and middle cerebellar and trigeminal arteries, and at the height of the rostral pons groove, divided into its two terminal branches, the rostral cerebellar and cerebral caudal arteries. The terminal branches of the basilar artery projected rostrally, forming the hypophyseal and rostral choroid arteries. The basilar artery passed the optic tract and bifurcated in the middle cerebral artery, its last collateral branch, and in the rostral cerebral artery, its terminal branch. The rostral cerebral artery formed the medial branch, closing the cerebral arterial circle caudally in 40% of the cases.Discussion: In rodents, variability of the cerebral arterial circle was observed due to the degree of atrophy of the internal carotid artery. The basilar artery was a rectilinear vessel of great caliber in all described rodents, and in rodents with a vertebro-basilar system, it was divided into its terminal branches after crossing the pons, forming the rostral cerebellar, hypophyseal, rostral choroid, caudal, middle and rostral cerebral arteries. The caudal cerebellar artery had variation of origin and sometimes duplication. The median cerebellar artery, a collateral branch of the caudal cerebellar artery, was a branch of the basilar artery in capybara. The caudal cerebral artery had variations between rodents. In capybara, chinchilla and nutria the middle cerebral artery was the collateral branch of the terminal branches of the basilar artery, and distributed on the convex surface of the cerebral hemisphere. The rostral cerebral artery, a branch of the terminal branch of the basilar artery, was a branch of the internal carotid artery in other rodents, forming the medial branch, which was anastomosed with that of the opposite antimer, when present, forming the rostral communicating artery. In nutria, the cerebral arterial circle was closed caudally in all cases, as in other rodents, however, it was opened rostrally in 60% of cases, compared to 70% in chinchilla and 10% in capybara.

Systematization, Description and Territory of The Middle and Rostral Cerebral Arteries in Broad-Snouted Caimans (Caiman latirostris)

Background: Information on the arterial vascularization of the broad-snouted caimans’ brain (Caiman latirostris), a specie from the Brazilian fauna, is inexistent and the literature consulted yielded only one description about the development of embryonic circulation and post-birth cerebrovascular alterations in the brain of three caymans. The objective of this study was to describe and systematize the cerebral arterial vascularization of this reptile, by providing a standard irrigation model with its major variations, in addition to determining its territorial vascular areas. Materials, Methods & Results: Thirty heads of male broad-snouted caimans (Caiman latirostris), with the neck segment, were used in the study. Additionally, two whole female and male specimens, with approximately 3 years of age and weighing between 8 to 10 Kg were also used. The animals were sacrificed according to routine slaughterhouse norms. The heads were sectioned at the third cervical vertebra level and the azygos carotid artery was cannulated. The arterial system was washed with 0.9% saline solution and filled with red-colored latex. The pieces were fixed in formaldehyde and the encephalon removed through a window made in the cranial vault, which was followed by removal of the dura mater and dissection of the arteries. The internal carotid arteries displayed an intercarotic anastomosis in the samples examined, continuing rostrally in 100% of the cases, exiting from the skull as the internal ophthalmic artery. The internal carotid arteries divided into a rostral branch and a short caudal branch at the hypophysis level, which continued naturally as the caudal cerebral artery. The rostral branch from both right and left antimeres was shown as a single branch in 86.7% and as double branch in 13.3% of the samples, and it formed the middle cerebral artery network. The rostral cerebral artery represented the terminal branch of the internal carotid artery’s rostral branch, and an osculum anastomosis between its terminal end and its contralateral homologous artery occurred, forming the rostral communicating artery and thus closing the cerebral artery circle rostrally. Discussion: To support the results of the discussion, we used information available on the encephalic vascularization of turtles, lizards, iguanas and crocodiles, due to the absence of important publications about Caiman latirostris. One single source of blood supply, solely originated from the left aortic arch, was observed in the two whole specimens. This source was called the azygos carotid artery. Such denomination was given because these species did not show a typical common carotid artery, as the ventral part of the neck, up to the mandible, was vascularized by branches from the subclavian arteries. Therefore, we named this single and unique source as the azygos carotid artery. The cerebral arterial circle was rostrally closed by an anastomosis between the terminal ends of the rostral cerebral artery. Consequently, the blood supply to the brain was made exclusively by the carotid system. The main differences of the cerebral vascularization observed in caymans were: a network formation of the middle cerebral artery.

Internal Ophthalmic Arteries Within the Brain-Base Arterial System in Guinea Pig.

In situ vascular specimens of the arterial circle were collected from 15 adult guinea pigs, both male and female. After specimen preparation, the vessels were filled with synthetic latex and subjected to analysis. Similar as in the case of other rodents, vertebral arteries were merged into basilar artery, further dividing into two short terminal branches. Distally, the terminal branches extend into caudal cerebral arteries. Rostral part of the arterial circle of brain is supplied with blood from maxillary arteries via external and internal ophthalmic arteries connected by a short anastomosis. This type of vascularity may probably be considered a functional analogy to the internal carotid arteries observed in other species. Rostral and caudal parts of the arterial circle of brain are connected by exceptionally long caudal communicating arteries. In author's opinion, the disputable contribution of internal carotid artery and the exceptional contribution of internal ophthalmic arteries in the cerebral blood supply in guinea pigs as compared to other rodents, warrants further research on the subject. Anat Rec, 301:887-891, 2018. © 2017 Wiley Periodicals, Inc.

Systematization and description of the internal carotid arteries and their main ramifications at the brain base in turtles (Trachemys scripta elegans).

Thirty turtle brains (Trachemys scripta elegans) were injected with latex to systematize and describe the internal carotid arteries and their main ramifications at the brain base. The internal carotid arteries had one intercarotid anastomosis. At the level of the tuber cinereum, the internal carotid artery bifurcated into its terminal branches, the rostral and the caudal branches. The rostral branch emitted the rostral choroid artery, the orbital artery, and a series of middle cerebral arteries. After giving off the last middle cerebral artery, the rostral branch continued as the rostral cerebral artery in the cerebral longitudinal fissure, and had one anastomosis with its contralateral homologous artery, the rostral communicating artery, making the first rostral closure of the cerebral arterial circle. Next, the rostral cerebral arteries anastomosed forming a rostral interhemispheric artery, making the second rostral closure of the cerebral arterial circle. The internal carotid artery, after emitting its rostral branch, continued caudally as the caudal branch. The caudal branch ran caudally along the ventral surface of the mesencephalic tegmentum, emitted the caudal cerebral artery and the mesencephalic artery, and continued caudomedially while progressively narrowing, and anastomosed with its contralateral homologous artery, forming the basilar artery. The narrower portion also emitted the trigeminal artery. The anastomosis of the caudal branches closed the cerebral arterial circle caudally. The internal carotid arteries exclusively supplied the cerebral arterial circle of the turtle. Anat Rec, 299:1090-1098, 2016. © 2016 Wiley Periodicals, Inc.

Arterial vascularization of the brain of the agouti (Dasyprocta aguti Linnaeus, 1766)

The agouti, a rodent that is geographically distributed throughout South America, is greatly valued for its meat. This paper describes the arterial vascularization of the base of the agouti’s brain, characterizing behavior, and arterial origin and distribution. Ten animals from the Center for the Multiplication of Wild Animals (CEMAS/UFERSA) were used and the study was approved by SISBIO (report number 32413- 1) and the Ethics Committee on Animal Use (CEUA/UFERSA) (protocol 02/2010). After euthanasia, the animals were incised in the thoracic cavity by an injection of red-stained Neoprene latex 650 and the skulls were subsequently opened. The brains were extracted from the skulls for ventral surface analysis and then fixed in an aqueous 10% formaldehyde solution. The agouti’s arterial vascularization of the brain has two main components, namely the carotid and vertebrobasilar systems. The agouti’s carotid system accounts for vascularization of almost the entire forebrain, while the vertebrobasilar system accounts for vascularization of almost the entire posterior brain (medulla oblongata, pyramid, trapezoid body, cerebellum, bridge, and part of the third caudal section of the forebrain) through the caudal cerebral arteries originating from the terminal branches of the basilar artery. The main arteries on the brain surface include the basilar artery, which is unique, and the arterial pairs, specifically the vertebral arteries, cerebellar caudal arteries, trigeminal artery, rostral cerebellar artery, basilar terminal branch artery, cerebral caudal artery, communicating caudal branch of the cerebral carotid artery, cerebral carotid artery, communicating branch rostral cerebral carotid artery, choroidal rostral artery, medial branch of the communicating branch rostral artery, internal ophthalmic artery, middle cerebral artery, and rostral cerebral artery.

Systematization, Description, and Territory of the Middle Cerebral Artery in Brain Surface of the Turtle (Trachemys scripta elegans)

Background: Trachemys scripta elegans, in Brazil, has been considered an exotic and invasive turtle; it competes with autochthon species for habitat and food, threatening biodiversity. These animals have been exported to Brazil as pets; however, despite of the commercial interest in the last years, there are only few reports about the turtle central nervous system vascularization. Therefore, this study had the objective to describe and systematize the middle cerebral artery at the brain surface of the turtle (Trachemys scripta elegans), determining a standard model of irrigation and the main ramifications and territory, in this species.Materials, Methods &amp; Results: Thirty turtles received pre-anesthetic medication composed of ketamine (80 mg/kg) and midazolam (2 mg/kg) followed by euthanasia with a sodium thiopental (100 mg/kg) overdose. The aortic arches were cannulated through the single ventricle, the cranial cava veins were incised and the vascular system washed with saline solution and heparin, and then filled with latex. Pieces remained immersed in running water and a bone window was opened in the cranial vault. Samples were fixed with formaldehyde and each brain with a spinal cord segment was removed from the cranial vault, the duramater was removed and the arteries dissected. Results were recorded and it was observed that the middle cerebral artery, collateral branch of the rostral branch of the internal carotid artery, varied between one to three components. These vessels anastomosed, originating a net that was projected from the base of the brain dorsorostralwards, reaching the convex surface of the olfactory bulb. Their lateral ramifications formed the convex hemispheric arteries, which ascended to the convex surface of the cerebral hemisphere and reached, caudally, the proximities of the caudal pole, anastomosing with the occipital hemispheric branches of the caudal cerebral artery and, dorsally, anastomosed with the caudal medial hemispheric branches of the caudal inter-hemispheric artery. Rostrally, its terminal branches, dorsal and ventral, formed a vascular ring around the coronal sulcus, which separated the cerebral hemisphere from the sessile olfactory bulb together with the rostral medial hemispheric branches of the rostral inter-hemispheric artery, branch of the rostral cerebral artery. The arteries of the olfactory bulb were originated from this ring. The middle cerebral artery in 63.4% of the samples to the right and in 56.7% to the left was double. But in 33.3% to the right and 20% to the left was triple, whereas in 3.3% to the right and in 23.3% to the left was a single vessel.Discussion: Authors reported that the middle cerebral artery, in reptiles, was originated as a single trunk, which subdivided into several arteries or was formed from several short trunks that ramified towards the convex surface of the cerebral hemisphere. In a study about turtles, the middle cerebral artery presented single origin and was emitted from the rostral branch of the internal carotid artery, emitting secondary branches that irrigated a portion of the dorsolateral surface of the cerebral hemispheres. In alligators, the rostral branch of the internal carotid artery originated a large middle cerebral artery, which emitted secondary branches towards the lateral surface of the cerebral hemisphere, continuing as rostral cerebral artery. In Cayman, the middle cerebral artery consisted of a formation of a net originated from one to five vessels, which was projected in sequence as collateral branches of the rostral branch of the internal carotid artery. This pattern of the middle cerebral artery was also observed in Trachemys, however, the net formation of the middle cerebral artery was after the emission of one to three vessels.

The Arteries of the Brain in Hare (Lepus europaeus Pallas, 1778)

Research into course and variability of brain arteries in hare were performed on 38 adult hares of both sexes (males 23 and females 15). The arteries were filled with a synthetic latex at a constant pressure introduced with a medical syringe to the left ventricle. The source of blood supply to the brain was internal carotid arteries, whose branches formed an arterial circle of the brain, vertebral arteries, and basilar artery as the result of its anastomosis. Variability focused on a method of departure of middle cerebral arteries, which were multiple vessels in 39.5% of cases and rostral cerebellar arteries. Caudal communicating arteries in hare comprised bilateral anastomosis of internal carotid arteries and final branches of the basilar artery. It stabilized the steady flow of blood to all parts of the brain. Caudal cerebral arteries comprised final branches of the basilar artery. The largest capacity of all the arteries of the brain was observed in the main trunk of the basilar artery. The capacity of these vessels was 4.53 mm(3) on average. The factor of capacity of cerebral arteries in relation to weight of the brain reaches a high value in hare.

Systematization, distribution and territory of the caudal cerebral artery on the brain's surface of the turkey (Meleagris gallopavo)

Thirty Meleagris gallopavo heads with their neck segments were used. Animals were contained and euthanized with the association of mebezonium iodide, embutramide and tetracaine hydrochloride (T 61, Intervet ) by intravenous injection. The arterial system was rinsed with cold saline solution (15°C), with 5000IU heparin and filled with red-colored latex. The samples were fixed in 20% formaldehyde for seven days. The brains were removed with a segment of cervical spinal cord and after, the dura-mater was removed and the arteries dissected. The cerebral carotid arteries, after the intercarotid anastomosis, were projected around the hypophysis, until they reached the tuber cinereum and divided into their terminal branches, the caudal branch and the rostral branch. The rostral branch was projected rostrolateralwards and gave off, in sequence, two collateral branches, the caudal cerebral and the middle cerebral arteries and the terminal branch was as cerebroethmoidal artery. The caudal cerebral artery of one antimere formed the interhemispheric artery, which gave off dorsal hemispheric branches to the convex surface of both antimeres. Its dorsal tectal mesencephalic branch, of only one antimere, originated the dorsal cerebellar artery. In the interior of the cerebral transverse fissure, after the origin of the dorsal tectal mesencephalic artery, the caudal cerebral artery emitted occipital hemispheric branches, pineal branches and medial hemispheric branches, on both antimeres. The caudal cerebral artery's territory comprehended the entire surface of the dorsal hemioptic lobe, the rostral surface of the cerebellum, the diencephalic structures, the caudal pole and the medial surface of the cerebral hemisphere and in the convex surface, the sagittal eminence except for its most rostral third. Due to the asymmetry found in the caudal cerebral arteries' ramifications, the models were classified into three types and their respective subtypes.

Systematization, description, and territory of the caudal cerebral artery in surface of the brain of the ostrich (Struthio camelus).

Brain specimens from 30 ostriches were injected with red-dyed latex via the internal carotid arteries, and the caudal cerebral arteries and their branches were systematically described. On the right side, the caudal cerebral artery was double-, triple-, quadruple-, and single-branched in 73.5%, 23.3%, 3.3%, and 3.3% of cases, respectively; on the left side, it was double-, triple-, quadruple-, and single-branched in 76.7%, 20%, 3.3%, and 3.3% of cases, respectively. The dorsal tectal mesencephalic artery appeared as a single vessel in 96.7% of cases, emerging as a collateral branch of the caudal cerebral artery. The dorsal mesencephalic tectal artery originated from the right dorsal cerebellar artery in 40% of cases and from the left side in 63.3% of cases. On the right side, there were four and three medial occipital hemispheric branches in 46.7% and 20% of cases, respectively; on the left side, there were four and three branches in 30% and 26.7% of cases. On the right side, the pineal artery was double-, single-, triple-, and quadruple-branched in 50%, 23.3%, 20%, and 6.7% of cases, respectively; on the left side, this artery was double-, single-, triple-, and quadruple-branched in 50%, 23.3%, 16.7%, and 10% of cases, respectively. The diencephalic artery was on the right side in 43.3% of cases and on the left side in 56.7% of cases. The interhemispheric artery was on the right side in 56.7% of cases and on the left side in 43.3% of cases; four, three, two, five, and one dorsal hemispheric trunks branched off of the interhemispheric artery in 40%, 40%, 10%, 6.7%, and 26.7% of cases, respectively. The caudal cerebral artery was classified as Type I in 56.7% of cases (subtype IA in 33.3% of cases and IB in 23.3% of cases), Type II in 40% of cases (subtype IIA in 20% of cases and IIB in 20% of cases), and Type III in 3.3% of cases.