LAUSR

The brain arteries derived from 50 adult degu individuals of both sexes were injected with synthetic latex introduced with a syringe into the left ventricle of the heart under constant pressure. After fixation in 5% formalin and brain preparation, it was found that the sources of the brain's supply of blood are vertebral arteries and the basilar artery formed as a result of their anastomosis. The basilar artery gave rise to caudal cerebellar arteries and then divided into two branches which formed the arterial circle of the brain. The internal carotid arteries in degus, except for one case, were heavily reduced and did not play an important role in the blood supply to the brain. The arterial circle of the brain in 48% of the cases was open from the rostral side. Variation was identified in the anatomy and the pattern of the arteries of the base of the brain in the degu which involved an asymmetry of the descent of caudal cerebellar arteries (6.0%), rostral cerebellar arteries (8%) as well as middle cerebral arteries (12%). In 6% of the individuals double middle cerebral arteries were found. In one out of 50 cases there was observed a reduction in the left vertebral artery and the appearance of the internal carotid artery on the same side. In that case the left part of the arterial circle of the brain was supplied with blood by an internal carotid artery, which was present only in that animal.