Arterial supply and venous drainage of the brain of the black bear (Ursus americanus). II.Intracranial microvasculature

A morphological study of the intracranial microvasculature of the Black bear (Ursus americanus) using vascular casts was undertaken. The object was to provide basic information regarding structural modifications of the microvasculature that might provide insight into the ability to cope with low blood flow states that occur during winter sleep. Vascular casts were prepared from 6 animals.The microvasculature of the brain disclosed characteristic features of the small vessels in mammals, including vascular sphincters of two types and numerous arterial and arteriolar anastomoses.