Comparative Morphology of the Arterial Circle of the Brain in Some Species of Mammals.

Investigations were performed on 10 adult individuals of chinchilla ( Chinchilla laniger), midday gerbil ( Gerbillus gerbillus), rabbit ( Oryctolagus cuniculus), guinea pig ( Cavia porcellus) and Egyptian spiny mouse ( Acomys cahirinus). The animals were killed with ether anaesthesia and injected with coloured acryl latex through the abdominal aorta or left heart ventricle. The heads of the animals were fixed in formalin and after decalcification in 5% HNO3, injected arteries of the base of the brain were exposed. The different types of arterial circle of the brain in investigated species were observed. The open type with morphological asymmetry in the anterior part was found in chinchilla. It depended on an unusually strongly developed anterior cerebral artery at the right side. In the midday gerbil the most common form was the closed type of investigated circle, with a lack of typical communicating artery posterior. The morphological asymmetry of the anterior part of the circle without fully developed anterior cerebral artery was found in the rabbit. Typical, the closed type of investigated structure with little individual variability was observed in guinea pig. The most individual variability connected with anterior and posterior part of the Willi's circle was found in the Egyptian spiny mouse where it was difficult to describe the typical arterial circle of the base of the brain. [ABSTRACT FROM AUTHOR]