RESUMEN
BACKGROUND: Although centuries of the human CAC research are behind us, still there is a stimulus for the authors to describe something new or to add to the "archive" of already known facts about its angioarchitecture. METHODS: With normal configurations of the posterior part of the CAC in early prenatal status, 172 brains of human fetuses from the 13th to the 24th week were used in the purpose of investigation. Brain arteries were injected and microdissected using a surgical microscope. RESULTS: According to diameter values of vascular components in the posterior part of the CAC, 6 basic types and the corresponding number of their subtypes are formed. Incidences of bilateral transitory (18.6%), fetal (9.3%), and adult (33.1%) types, as well bilateral asymmetric types (fetal-transitory in 5.8%, adult-transitory in 14.5%, and adult-fetal in 18.6% of cases), proved that dominant configuration of posterior part had not been present in the period from the fourth to the sixth gestational month. CONCLUSION: The finding of normal subtypes of the posterior part of the CAC, as well as the absence of some subtypes, is a challenge for future studies of the posterior arterial pattern within vascular abnormalities or diseases.