engleski

Early lamination of the cortical plate in the prefrontal cortex of the human fetus: in vitro 3T MR imaging and histological analysis

The cortical plate is a transient fetal layer predominantly composed of densly packed postmigratory neurons arranged in radial columns. In the human fetal neocortex, CP appears around 8th postconceptional week (PCW), undergoes dynamic cellular changes, and disappears near term, when it transformes into a six-layered cortical "Grundtypus". The first sub-lamination within the CP occurs at 24 PCW, in parallel with the ingrowth of thalamocortical axons. We analyzed appearance and regional extent of CP lamination in the human fetal prefrontal cortex by using postmortem (in vitro) MR imaging on a 3T device and by comparing these images with serial histological sections obtained from Zagreb Embryological Collection. For image analysis 34 fetal brains raging between 13 and 40 PCW were scanned. The earliest loosening of CP occurs at 13 PCW when deep part of the frontal CP transforms into the subplate zone. The earliest sublamination within the CP develops between 20 and 23 PCW in the midlateral frontal neocortex in a form of a low signal intensity band on T1 weighted images. On histological sections cortical sub-lamination is seen one week earlier. This laminar event occurs simuntaneously in the lateral, parietal, occipital and temporal neocortex. The developmental appearance of CP sublamination coincides with accumulation and subsequent ingrowth of thalamocortical fibers as seen on histochemical preparations. In term newborns CP sublamination becomes obscured due to the overall decrease of cell density and the formation of basic six-layered pattern. We conclude that MR imaging at high resolution (3T) shows laminar organization comparable to nissl images and that the appearance of CP sublamination coincides with the ingrowth of thalamocortical fibers. The imaging parameters obtained in present study will be used for future in vivo studies of important cortical histogenetic events.

prefrontal cortex; magnetic resonance; cortical lamination; human

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