title: Variation in form of circle of Willis: some anatomical and embryological considerations.
abstract: This work is based on a study of 62 circles of Willis (circulus arteriosus cerebri) from patients dead from diverse causes. We have described the wide diversity of variations found to be present in the arterial vessels that form the circle, we presented the frequency of the different variations, and finally we discuss the possible ontogenic cause of these variations.
mesh_terms: D002539:Cerebral Arterial Diseases / Q000453:epidemiology; D002536:Cerebral Arteries / Q000002:abnormalities; D002941:Circle of Willis / Q000033:anatomy & histology* / Q000196:embryology; D005260:Female; D014644:Genetic Variation; D006801:Humans; D008297:Male