Introduction: Cerebral hemodynamics undergoes a shift from carotid system to vertebro-basilar system from fetal stage to adult life. The circle of Willis (CW) plays a major role in redistributing the blood and enables interhemispheric flow through the anterior & posterior communicating arteries (AComA, PComA). The text book description mention three stages in the development of CW- fetal, transitional and adult. The purpose of the present study was to observe development of arterial anastomoses during intrauterine life, to note the variations and trying to explain some of the hypothesis for these variations.
Material & Method: The material of the present study include 45 fetal brains of different age groups. Variations were observed regarding absence, duplication, bilateral asymmetry and tortuousity.
Results: The number and type of variations in fetus were lesser as compared to adults. Anomalies including presence of aneurysm, absence of anterior cerebral artery (ACA) and splitting of a constituent vessel were not observed in fetal brains. However there were incidences of absence / duplication and hypoplasia of a component vessel. During early gestation period, all the cerebral vessels were slender but uniform in size. This is named as fetal stage. After 22nd wks of fertilization, due to rapid development of occipital lobes, there is increase in the diameter of either posterior cerebral artery (PCA) or PComA thereby giving rise to either adult or transitional type of configuration respectively.
Fetal brains;Circle of Willis;Variations