Composition of encephalic arteries and origin of the basilar artery are different between vertebrates.

Intracranial arterial anatomy is lacking for most mammalian and non-mammalian model species, especially concerning the origin of the basilar artery (BA). Enhancing the knowledge of this anatomy can improve animal models and help understanding anatomical variations in humans. We have studied encephalic arteries in three different species of birds and eight different species of mammals using formalin-fixed brains injected with arterial red latex. Our results and literature analysis indicate that, for all vertebrates, the internal carotid artery (ICA) supplies the brain and divides into two branches: a cranial and a caudal branch. The difference between vertebrates lies in the caudal branch of the ICA. For non-mammalian, the caudal branch is the origin of the BA, and the vertebral artery (VA) is not involved in brain supply. For mammals, the VA supplies encephalic arteries in two different ways. In the first type of organization, mostly found in ungulates, the carotid rete mirabile supplies the encephalic arteries, the caudal branch is the origin of the BA, and the VA is indirectly involved in carotid rete mirabile blood supply. The second type of encephalic artery organization for mammals is the same as in humans. The caudal branch of the ICA serves as the posterior communicating artery, and the BA originates from both VAs. We believe that knowledge of comparative anatomy of encephalic arteries contributes to a better understanding of animal models applicable to surgical or radiological techniques. It improves the understanding of rare encephalic variations that may be present in humans.

Interventions and imaging in patients with anatomic variations of cerebral circulation: a pictorial review.

The cerebral arterial system shows a wide spectrum of variations. Minor degrees of anatomic differences can be seen in almost all patients. Recognition of these anatomic variants is essential for the following: evaluating collateral circulation; some anatomic variants may mimic pathology; increased risk for aneurysm formation with some variants (e.g. fenestration, persistent trigeminal artery); dealing with pathologies that can arise with these variations; and for preoperative planning. The anterior and posterior groups of intracranial circulation show numerous anastomoses that play a major role in maintaining adequate blood supply to the cerebral parenchyma. This review focuses on the imaging features of these variants as seen on computed tomography and magnetic resonance imaging with relevant digital subtraction angiography imaging. We also present some case illustrations where understanding of these variants contributed to providing appropriate management.

Sheep-Associated Malignant Catarrhal Fever: Role of Latent Virus and Macrophages in Vasculitis.

Malignant catarrhal fever (MCF) is a sporadic, generally fatal disease caused by gammaherpesviruses in susceptible dead-end hosts. A key pathological process is systemic vasculitis in which productively infected cytotoxic T cells play a major role. Nonetheless, the pathogenesis of MCF vasculitis is not yet clear. We hypothesized that it develops due to an interaction between virus-infected cells and immune cells, and we undertook a retrospective in situ study on the rete mirabile arteries of confirmed ovine gammaherpesvirus-2 (OvHV-2)-associated MCF cases in cattle, buffalo, and bison. Our results suggest that the arteritis develops from an adventitial infiltration of inflammatory cells from the vasa vasorum, and recruitment of leukocytes from the arterial lumen that leads to a superimposed infiltration of the intima and media that can result in chronic changes including neointimal proliferation. We found macrophages and T cells to be the dominant infiltrating cells, and both could proliferate locally. Using RNA in situ hybridization and immunohistology, we showed that the process is accompanied by widespread viral infection, not only in infiltrating leukocytes but also in vascular endothelial cells, medial smooth muscle cells, and adventitial fibroblasts. Our results suggest that OvHV-2-infected T cells, monocytes, and locally proliferating macrophages contribute to the vasculitis in MCF. The initial trigger or insult that leads to leukocyte recruitment and activation is not yet known, but there is evidence that latently infected, activated endothelial cells play a role in this. Activated macrophages might then release the necessary pro-inflammatory mediators and, eventually, induce the characteristic vascular changes.

Comparing N-hexyl cyanoacrylate (Magic Glue) and N-butyl cyanoacrylate (NBCA) for neurovascular embolization using the pressure cooker technique: An experimental study in swine.

BACKGROUND: The pressure cooker (PC) technique uses a second microcatheter to produce a proximal occlusion to prevent the reflux of liquid embolic agent (LEA) injected through a more distal microcatheter, and can be used to treat arteriovenous malformations and dural arteriovenous fistulae. The liquid embolic Magic Glue (MG) (N-hexyl cyanoacrylate (NHCA)) has been introduced as an alternative to N-butyl cyanoacrylate (NBCA). Our goals were to compare the extent of embolization of rete mirabile with or without the PC technique using NBCA or MG, and to compare the proximal occlusions obtained with MG or NBCA while using the PC technique in a renal arterial model. METHODS: Rete mirabile were embolized with (n = 4) and without (n = 4) the PC technique, using MG (n = 4) or NBCA (n = 4). A renal arterial model was then used to study the characteristics of the MG plug (n = 10) used for the PC technique, and resistance to catheter withdrawal as compared to NBCA (n = 4). Specimens were analyzed macro- and microscopically and compared to angiographic results. RESULTS: Extent of rete embolization with CYA agents was not significantly greater when using the PC technique. Results were similar with both types of cyanoacrylate (p = 0.657). The force necessary to withdraw the microcatheter was less with MG than with NBCA (p = 0.035). CONCLUSION: MG was similar to NBCA in extent of rete embolization. Less traction force was necessary to withdraw trapped non-detachable microcatheters using MG compared to NBCA.

Spontaneous recession of a posterior cerebral artery aneurysm concurrent with carotid rete mirabile and moyamoya-pattern collateral vessels: a case report.

BACKGROUND: Carotid rete mirabile (RM) is a meshwork of multiple, freely intercommunicating arterioles that reconstitute the absent or hypoplastic segments of the internal carotid artery (ICA). Carotid RM has been reported to be associated with cerebrovascular diseases. However, it is rarely associated with moyamoya-pattern collateral vessels in the posterior cerebral artery (PCA) region and aneurysm. CASE PRESENTATION: A 39-year-old woman was admitted complaining of sudden-onset headache, nausea, and vomiting. Further investigation revealed subarachnoid hemorrhage (SAH), carotid RM, a moyamoya collateral pattern in the PCA region, and a pseudoaneurysm in the moyamoya-like vessels. The patient was treated conservatively, recovered well and was discharged 1 week later. Follow-up angiography showed that the aneurysm had disappeared. CONCLUSIONS: As shown by the present case, we believe that carotid RM could occur in combination with moyamoya-pattern collateral vessels in the PCA region; aneurysms can occur in the moyamoya-like vascular network. Congenital etiology may be the reason for these combinations. Based on our approach in this case, aneurysm located in moyamoya-like vessels can disappear spontaneously after conservative treatment.

Isolation of right internal carotid artery, persistent proatlantal 1 artery and rete mirabile in a child with 22q11 deletion syndrome.

We report a case of a 2-year-old girl with 22q11 deletion syndrome who underwent studies for cardiac murmur. Ultrasound, computed tomography angiography and digital subtraction angiography revealed an aberrant right subclavian artery and an isolated right internal carotid artery (ICA) originating from the right pulmonary artery. A right carotid rete mirabile (CRM) and a proatlantal (Pa) type 1 artery were also found. We hypothesize that Pa type 1 persistence and CRM development are secondary to the reversal of flow of the isolated ICA.

Transcript levels of members of the SLC2 and SLC5 families of glucose transport proteins in eel swimbladder tissue: the influence of silvering and the influence of a nematode infection.

The rate of glucose metabolism has been shown to be correlated to glucose uptake in swimbladder gas gland cells. Therefore, it is assumed that in the European eel silvering, i.e., the preparation of the eel for the spawning migration to the Sargasso Sea, coincides with an enhanced capacity for glucose uptake. To test this hypothesis expression of all known glucose transport proteins has been assessed at the transcript level in yellow and in silver eels, and we also included Anguillicola crassus infected swimbladders. Glucose uptake by rete mirabile endothelial cells could be crucial for the countercurrent exchange capacity of the rete. Therefore, this tissue was also included in our analysis. The results revealed expression of ten different members of the slc2 family of glucose transporters, of four slc5 family members, and of kiaa1919 in gas gland tissue. Glucose transporters of the slc2 family were expressed at very high level, and slc2a1b made up about 80% of all slc2 family members, irrespective of the developmental state or the infection status of the eel. Overall, the slc5 family contributed to only about 8% of all detected glucose transport transcripts in gas gland tissue, and the slc2 family to more than 85%. In rete capillaries, the contribution of sodium-dependent glucose transporters was significantly higher, leaving only 66% for the slc2 family of glucose transporters. Neither silvering nor the infection status had a significant effect on the expression of glucose transporters in swimbladder gas gland tissue, suggesting that glucose metabolism of eel gas gland cells may not be related to transcriptional changes of glucose transport proteins.

Thomas Willis, a pioneer in translational research in anatomy (on the 350th anniversary of Cerebri anatome).

The year 2014 marked the 350th anniversary of the publication in London of Cerebri anatome, a ground-breaking work of neuroscience heavily influenced by the political and cultural context of Baroque Europe and mid-17th century England. This article aims to review the work of the English physician and anatomist Thomas Willis, specifically with regard to the contents of his Cerebri anatome. Willis's academic and professional career was influenced by the turbulent period of the English Civil War during which he studied medicine. Willis went from chemistry to dissection arguably because of his need to justify the body-brain-soul relationship. As a result, he became a fellow of a select club of eminent experimentalists, and afterward was a Fellow of the Royal Society. Later on, he went to London, leaving the academic life to dedicate himself fully to the profession of medicine. As a physician, Willis did not base his practice on aphorisms but on a 'bench to bedside' approach to medicine, while studying neuroanatomy--covering embryology, comparative anatomy and pathological anatomy--as a basis for the comprehension of neurological pathology. He developed innovative anatomical methods for the preservation and dissection of the brain, injection of coloured substances and illustration of his findings. In Cerebri anatome, Willis recognized the cerebral cortex as the substrate of cognition. He also claimed that the painful stimuli came from the meninges, but not from the brain itself. He explained for the first time the pathological and functional meaning of the brain's circular arterial anastomosis, which is named after him. He also specified some features of the cranial origin of the sympathetic nerves and coined the term 'neurologie'. Cerebri anatome marked the transition between the mediaeval and modern notions of brain function, and thus it is considered a cornerstone of clinical and comparative anatomy of the nervous system. The new contributions and methods employed by Willis justify his place as a father of neurology and a pioneer of translational research.

Risks and advantages of using surface laser photogrammetry on free-ranging marine organisms: a case study on white sharks Carcharodon carcharias.

This study employed a non-lethal measurement tool, which combined an existing photo-identification technique with a surface, parallel laser photogrammetry technique, to accurately estimate the size of free-ranging white sharks Carcharodon carcharias. Findings confirmed the hypothesis that surface laser photogrammetry is more accurate than crew-based estimations that utilized a shark cage of known size as a reference tool. Furthermore, field implementation also revealed that the photographer's angle of reference and the shark's body curvature could greatly influence technique accuracy, exposing two limitations. The findings showed minor inconsistencies with previous studies that examined pre-caudal to total length ratios of dead specimens. This study suggests that surface laser photogrammetry can successfully increase length estimation accuracy and illustrates the potential utility of this technique for growth and stock assessments on free-ranging marine organisms, which will lead to an improvement of the adaptive management of the species.

Johann Vesling (1598-1649): seventeenth century anatomist of Padua and his Syntagma Anatomicum.

Johann Vesling (1598-1649) was a German anatomist and surgeon who belonged to the golden period of the illustrious University of Padua. He made significant contributions to the advancement of anatomical knowledge during the 17th century and is remembered most for his remarkable anatomical work, the Syntagma Anatomicum, which was published in 1641. He was the first to describe the soleus muscle and to emphasize its resemblance to the sole fish. He produced the earliest illustrations of the human lymphatic system and was one of the first to document observations about the thoracic duct. He was also the first to report the bifurcation of the human hepatic portal vein on entering the fissure of the liver. His observations from embryological experiments were critical for understanding the development of the four-chambered heart. He was one of the first authors to state that four pulmonary veins empty into the left atrium of the heart. Syntagma Anatomicum (1641) was the most widely used anatomical text in Europe for almost a century and was republished a number of times with editions in Latin, German, Dutch, and English. Syntagma was the first illustrated western anatomical text to reach Japan and laid the foundation for the development of European medicine there. The illustrations used in it deviated from the artistic convention that had characterized anatomical figures from the time of Vesalius, and focused instead on representing anatomical details to make them helpful for medicine and surgery. Clin. Anat. 27:1122-1127, 2014. © 2014 Wiley Periodicals, Inc.

Fascinating wonderful network: Rete mirabile of the maxillary artery in cats - minireview.

Cats are one of the most common companion animals, and they differ from dogs in several important ways. Considering the central importance of anatomy in high-quality medicine, the treatment of the feline mandible, mostly during intraoral procedures requiring general anaesthesia, has many important features. In cats, the major artery of the brain is the maxillary artery that forms unique structure - the rete mirabile. The rete mirabile is a plexus like vascular structure that lies extracranially and communicates with brain arterial circle through the orbital fissure. The development of the brain vasculature is different in cats, and it includes obliteration mechanisms of the internal carotid artery. The course of the maxillary artery that forms the rete mirabile has a strong relationship to the angular process of the mandible. Emphasis should be placed on manipulation with the feline mandible, especially during open-mouth procedures, as mistakes can lead to blindness, deafness, and central neurological disorders due to compression of the maxillary artery by the angular process of the mandible. This paper focuses on the anatomy and function of the blood supply to the brain, which is very specific in domestic cats and other felids.

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.

Coexistence of anterior choroidal artery and posterior cerebral artery retia mirabilia presenting with subarachnoid hemorrhage: illustrative case.

BACKGROUND: A rete mirabile is a rare vascular anomaly, with posterior cerebral artery (PCA) involvement being especially rare. Its pathogenesis has been speculated as a remnant of "distal annexation" between the primitive anterior choroidal artery (AchA) and the PCA at this site, but the exact mechanisms remain unclear. OBSERVATIONS: A 29-year-old man presented with subarachnoid hemorrhage. Arteriovenous malformation in the medial temporal lobe was initially suspected, but an arteriovenous shunt was not detected. First, conservative treatment was administered; however, rebleeding occurred 1 month later. Carotid angiography revealed a network-like cluster of blood vessels at the choroidal point of the AchA, suggesting a rete mirabile; these vessel clusters led to the persistent temporo-occipital branch of the AchA. Furthermore, an aneurysm was detected at the junction between the rete mirabile and the persistent temporo-occipital branch of the AchA. Additionally, vertebral angiography demonstrated a rete mirabile at the P2 segment. These findings suggested the coexistence of AchA and PCA retia mirabilia. Consequently, the aneurysm was clipped using a subtemporal approach to prevent re-rupture, and the postoperative course was uneventful. LESSONS: This first report of coexisting AchA and PCA retia mirabilia supports the remnant of distal annexation between the primitive AchA and the PCA as the reason for rete formation at this site.

Arterial circle of the brain in the common wildebeest (Connochaetes taurinus).

The main aim of this study was to analyze the arterial circle of the brain and rostral epidural rete mirabile in specimens of the common wildebeest (Connochaetes taurinus). The arterial circle of the brain is a circulatory anastomosis that supplies blood to particular lobes of the brain and surrounding structures. The study was conducted on male and female adults (n = 12) by bilateral injection of an acetone solution of vinyl superchloride or latex LBS3060, which resulted in a cast of arteries of the head and encephalic base. We describe the exact structure of the arterial circle of the brain and rostral epidural rete mirabile. The shape of the arterial circle of the brain in the common wildebeest is heart-shaped, as in other Bovidae. It is formed by bilateral rostral cerebral arteries, caudal communicating arteries, and the basilar artery, with a general pattern of vessels forming and branching off from the arterial circle of the brain, as described in other ruminants. The rostral cerebral and caudal communicating arteries emerge from an intracranial segment of the internal carotid artery, which in turn arises from vessels of the rostral epidural rete mirabile. This structure, well developed in the examined individuals, has mechanisms underlying selective cooling of the brain, protecting animals from hyperthermia, and affecting body water balance.

Revised concept of rete-like collateral formation: Rete mirabile does not exist in humans.

The carotid rete is a physiological network between the external and internal carotid arteries (ICA) in lower vertebrates. However, true carotid rete does not exist in humans. This review aimed to contrast the physiological function of human "rete-like collaterals" with that of lower vertebrate "rete mirabile". An explanation for the development of rete-like collaterals in human intracranial arteries was also discussed. The rete mirabile (carotid, vertebral, spinal, and thoracic) in lower vertebrates has a specific physiological role and does not form vasculature for the same purpose in humans. Therefore, the term "rete mirabile" should not be used for cases reported in humans. Instead, "rete-like collaterals" is preferred. In the literature, rete-like or arterial anastomosis was observed in the ICA cavernous portion and the intradural arteries. Based on the hypothesis of the segmental concept, it applies to the ICA and intracranial arteries. Whether in the ICA, middle cerebral artery, posterior cerebral artery, or posterior inferior cerebellar artery, the segmental concept is the same and should be considered to have formed secondary collaterals after segmental regress or dysgenesis of affected arteries. Summarily, the significance of this review lies in its reevaluation of vascular structures previously described as "carotid rete" in humans to a true and preferred term, "rete-like collaterals". It also provides insights into the historical context and potential genetic factors associated with the formation of arteries in humans, contributing to a better understanding of human vascular anatomy.

The rete mirabile: a possible control site for swimbladder function.

In a recent study, a large number of transport proteins was detected in the transcriptome and proteome of saline perfused rete mirabile tissue of the European eel. In this study, the data set was reanalyzed for the presence of receptor proteins and proteins involved in intracellular signaling pathways. A large number of expressed receptor proteins and proteins involved in intracellular signal transduction was detected. Several G-protein-coupled receptor signal pathways were significantly enriched in their expression level, in particular receptors and signaling pathways involved in the control of blood flow. The enriched signaling pathways also include pathways involved in trafficking of crucial transport proteins like, monocarboxylate transporters, V-ATPase, and aquaporin. The data, therefore, suggest that the rete mirabile has the capacity to control swimbladder function by regulating blood flow and by modifying countercurrent multiplication.

Cerebrovascular disorders associated with agenesis of the internal carotid artery: Findings on digital subtraction angiography.

Objective: Agenesis of the internal carotid artery (ICA) is a rare vascular condition that is complicated by intracranial aneurysms and rete mirabile. The altered hemodynamics caused by this distinctive cerebrovascular angioarchitecture can cause ischemic or hemorrhagic accidents. Data on clinical and radiographic features have been limited to describing this vascular pattern. We present five cases of agenesis of the internal carotid artery confirmed by digital subtraction angiography (DSA) and further investigate the influence of altered angioarchitecture on the integrity of intracranial morphology. Methods: Cases of ICA anomalies were screened from the patients who underwent DSA in two hospitals. Clinical manifestation, radiographic features, management, and outcomes were retrospectively reviewed. Results: Five patients [mean age 44 years (range, 30-65 years)] were included. Two patients presented with subarachnoid hemorrhage, one with cognitive impairment, one with dizziness, and one with intermittent headache. DSA demonstrated that three cases were complicated by intracranial aneurysms, one by dural arteriovenous fistula, and one by rete aneurysm. Three patients underwent endovascular treatment and one underwent bypass surgery. No patient died or experienced cerebrovascular accident during short-term follow-up. Conclusions: ICA agenesis can be complicated by disorders such as intracranial aneurysm, rete aneurysm, and dural arteriovenous fistula. This suggests that ICA agenesis is associated with a tendency towards disrupted cerebrovascular homeostasis resulting from altered hemodynamics.

Pulmonary and Systemic Skeletal Muscle Embolism in a Beaked Whale with a Massive Trauma of Unknown Aetiology.

An adult female Sowerby's beaked whale was found floating dead in Hermigua (La Gomera, Canary Islands, Spain) on 7 December 2016. Severe traumas of unknown aetiology were attributed, and the gross and microscopic findings are consistent with catastrophic trauma as a cause of death. Rib fractures affected the intercostals, transverse thoracis skeletal muscles, and thoracic rete mirabile. Degenerated muscle fibres were extruded to flow into vascular and lymphatic vessels travelling to several anatomic locations into the thoracic cavity, including the lungs, where they occluded the small lumen of pulmonary microvasculature. A pulmonary and systemic skeletal muscle embolism was diagnosed, constituting the first description of this kind of embolism in an animal. The only previous description has been reported in a woman after peritoneal dialysis. Skeletal pulmonary embolism should be considered a valuable diagnostic for different types of trauma in vivo in wild animals. This is especially valuable when working with decomposed carcasses, as in those cases, it is not always feasible to assess other traumatic evidence.

Evolution of the myth of the human rete mirabile traced through text and illustrations in printed books: The case of Vesalius and his plagiarists.

Andreas Vesalius initially accepted Galen's ideas concerning the rete mirabile in humans. In 1538, Vesalius drew a diagram of the human rete mirabile as a plexiform termination of the carotid arteries, where the vital spirit is transformed into the animal spirit, before being distributed from the brain along the nerves to the body. In 1540, Vesalius demonstrated the rete mirabile at a public anatomy, using a sheep's head (due to his nascent realization that he could not demonstrate this adequately in a human cadaver, potentially eliciting ridicule). By 1543, Vesalius had fully reversed himself, denied the existence of the rete mirabile in humans, and castigated himself for his prior failure to recognize this error in Galen's works. Vesalius nevertheless illustrated both the Galenic conception of the rete mirabile in humans and a schematic of the rete mirabile in ungulates. He intended the 1543 diagram of the human rete mirabile as an example of a mistake that resulted from Galen's overreliance on animals as models of human anatomy. However, in spite of Vesalius's intentions, for more than a century afterward, his figure was repeatedly and perversely plagiarized by advocates for Galenic doctrine, who misused it as a purportedly realistic representation of human anatomy and generally omitted the contrary opinions of Berengario da Carpi and Vesalius. The protracted use of stereotyped representations of the rete mirabile in extant printed illustrations provides tangible documentation of the stagnation in anatomical thought in the sixteenth and seventeenth centuries.

Summarizing the medieval anatomy of the head and brain in a single image: Magnus Hundt (1501) and Johann Dryander (1537) as transitional pre-Vesalian anatomists.

Of the early-sixteenth century pre-Vesalian anatomists, Magnus Hundt in 1501 and Johannes Eichmann (known as Johann Dryander) in 1537 both attempted to summarize the anatomy of the head and brain in a single complex figure. Dryander clearly based his illustration on the earlier one from Hundt, but he made several improvements, based in part on Dryander's own dissections. Whereas Hundt's entire monograph was medieval in character, Dryander's monograph was a mixture of medieval and early-modern frameworks; nevertheless, the corresponding illustrations of the anatomy of the head and brain in Hundt (1501) and Dryander (Dryandrum 1537) were both essentially medieval. This article examines in detail the symbology of both illustrations within the context of the medieval framework for neuroanatomy and neurophysiology. These two woodcuts of the head and brain provide the most detailed pictorial representation of medieval cranial anatomy in a printed book prior to the work of Andreas Vesalius in 1543.