Very important process of the development and maturation of the brain the development of cerebral cortex is considered. The proliferation and differentiation of the ependymal cells precedes the process of neuroblast’s migration to the cerebral cortex. This process is running during 10 to 22 weeks of gestation and with the cellular apoptosis of 30–50% of neuroblasts is finnished. In some cases the neuroblasts will not achieve the site of predestination in cerebral cortex and the abnormal layers or bands of heterotopias in subependymal or subcortical spaces may be formed. The deffects of cortical grey matter as flat cortex (lissencephaly or agyria) or pachygyria (macrogyria) or polymicrogyria may be presented. This dysplastic phenomena as the genetic chromosomal deffects (17th or X chromosoms or 9th chromosom in tuberous sclerosis) or the influence of external factors in the brain embryogenesis are conditioned. The process of neuroblast’s migration very frequently is continually connected with the earlier stages of the brain embryogenesis. Authors demonstrate in 5 cases the changes of the neuroblast’s migration in MRI examination with the earlier disturbance of the cellular proliferation and differentiation, which as abnormalities (hydrocephalus, middle line deffects) may be demonstrated.

        Key words: lissencephaly – heterotophy – neuroblast’s migration – MRI