Morphometry and Variability of the Brain Arterial Circle in Chinchilla (Chinchilla laniger, Molina)

Abstract

Arterial circles of brains from 70 adult chinchillas were filled with synthetic latex. The arterial circle of the brain is formed as the result of vertebral arteries being merged into the basilar artery. Caudally, both vertebral arteries gave rise to the ventral spinal artery. The ventral spinal artery splits into tiny cerebellar vessels, the pontine and cochlear branches. Distally, the basilar artery ramified into two terminal branches that formed the arterial circle of brain, rostrally open in most cases (75%). The observed variability of the arterial circle of brain of chinchillas pertained to all elements of that circle. The greatest variability within the vessels of the circle of Willis in chinchillas was observed in 22 cases (31.4%) of internal ophthalmic arteries. In chinchillas, a trend toward slight variability within the arteries comprising the arterial circle of the brain was observed in 44 animals. This accounted for 62.8% of all cases. Only in three cases was the arterial circle of brain clearly symmetrical. At the same time, 23 animals (32.8%) revealed features of significant vascular variability within the brain base region. These consisted of disturbed geometry of the entire arterial circle, different levels of ramifications into individual arteries, as well as the number and diameter of arteries. No internal carotid arteries were observed in chinchillas apart from one atypical case in which the carotid artery extended unilaterally into the basilar artery. These investigations indicate on the significant variability of arterial circle in rodents. Anat Rec, 300:1472-1480, 2017. © 2017 Wiley Periodicals, Inc.

Vertebrobasilar Contribution to Cerebral Arterial System of Dromedary Camels (Camelus dromedarius)

“…In our study the caudal cerebellar artery in most of our samples had two roots that arose from the basilar artery about 7 mm apart (Figures 9, 12). A double root of the caudal cerebellar artery has been reported in camelids, chinchilla and deer (21,26,27,31). Contrastingly in cattle, goats and dogs the caudal cerebellar artery has been reported as having a single root of origin (3,25).…”

The Stapedial Artery in the Mongolian Gerbil (Meriones unguiculatus)

“…Under these circumstances, the external ophthalmic artery becomes a branch of the maxillary artery and is sometimes assisted by very well-developed internal ophthalmic arteries extending from the rostral part of the circle of Willis. A special characteristic and the high variability of the arterial blood supply of the orbit was described by Kuchinka (2015Kuchinka ( , 2017 in chinchillas, and by Ocal and Ozer (1992) in guinea pigs. In humans, Hayreh and Dass (1962) demonstrated several cases of the eyeball supply originating from the middle meningeal artery, while Bervini and Assaad (2014) described a case of the ophthalmic artery branching off from the anterior cerebral artery in humans.…”

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

“…Another cause of the discrepancies may consist in the variability of head vascular patterns within the brain‐base arterial circle which is a feature characteristic for rodents. Examples of such variability were reported with regard to internal ophthalmic arteries (ramifying from basilar artery) in chinchillas (Kuchinka ). No case reports were found in the literature that would include internal ophthalmic arteries being the only source of blood to the eyeball, with no external ophthalmic arteries branching off the maxillary arteries (Kuchinka ).…”

“…The cerebral vascular system in rodents, including the arterial circle of the brain, is characterized by significant variability. It has been described in numerous articles (Tandler, ; Pilleri ; Frąckowiak and Śmiełowski, ; Reckziegel et al, ; Frąckowiak, ; Araújo and Campos, ; Szczurkowski et al, ; Kuchinka et al, ; Brudnicki et al, ; Kuchinka, , ).…”