ABSTRACT
The origin of the blood supply to the brain and arteries of the ventral surface of the brain was studied in 31 adult chinchillas (Chinchilla lanigera). The arterial system was filled with latex 603 via the brachioencephalic trunk and the left subclavian artery, both of which arose from the aortic arch in most cases. The right and left internal carotid arteries (100% and 93.3%, respectively) did not contribute to the brain supply. The vertebral arteries were present in all cases and formed the basilar artery (96.7%) that gave off the ventral spinal artery caudally in all cases. The caudal cerebellar artery was single (80%) or double (20%) on the right, and single (70%) or double (30%) on the left. The rostral cerebellar artery was present as a caudal vessel on the right (73.3%) and on the left (70%), and as a rostral vessel in all cases. The rostral tectal artery was single in all cases. The caudal cerebral artery was single (53.3%), double (36.7%) or triple (10%) on the right, and single (46.7%), double (46.7%) or triple (6.7%) on the left. The hypophyseal artery was present in all cases. The internal ophthalmic artery was present only on the right (26.7%), or only on the left (23.3%). The middle cerebral artery was single in all cases on both sides. The rostral cerebral artery was present as a well-developed (96.7%) or vestigial (3.3%) vessel in both antimeres, gave off lateral arteries to the olfactory bulb and the median rostral inter-hemispheric artery, and ended as the internal ethmoidal artery. The cerebral arterial circle was open (70%) or closed (30%) rostrally, and closed caudally in all cases. The brain was supplied almost exclusively by the vertebral-basilar system.