Asymmetry and anomalies of the circle of Willis in fetal brain. Microsurgical study and functional remarks.
The arteries of the circle of Willis in fetal brains of 20-40 weeks of gestational age were studied with the operating microscope. The majority of fetuses were between 24-32 weeks of age. Our findings were as follows: 1) the average diameters of all segments were 4-5 times narrower than the average diameters in adults, and the average lengths of the same segments were 2-2.5 times shorter than the same lengths in adults; 2) the number of perforators corresponded with the perforating arteries in adults; 3) hypoplastic segments, as well as anomalies and variations, were identified; 4) calibers almost equal in size between the right and left corresponding segments were found in a high proportion of cases; 5) in the majority of cases a polygon, much like the "precarious" circle in adults, was dissected. The "fetal" or the "ideal" circles were found in a low proportion of cases.
D000328:Adult; D002941:Circle of Willis / Q000002:abnormalities* / Q000033:anatomy & histology; D005260:Female; D005315:Fetal Diseases / Q000150:complications / Q000473:pathology*; D006801:Humans; D002532:Intracranial Aneurysm / Q000150:complications / Q000473:pathology; D008866:Microsurgery; D011247:Pregnancy