Structural basis of developmental changes in the cytoarchitecture of human neocortex transplants

Early stages in development of transplants of the embryonal anlages of the human neocortex into the brain of mature rats have been studied at light optic level. The main attention has been paid to processes of proliferation, migration and differentiation of cells. Increasing amount of cells in the transplants takes place only at the expense of neuroepithelium; its reorganization results in a peculiar rearrangement of cells with formation of so called rosellas with numerous mitotically dividing cells. Owing to this growth the differentiating cells migrate from the rosellas radially, unlike their layer-by-layer organization in the control. These deviations are probably dominant in the disturbance of cytoarchitectonic organization of cells in transplants of neocortex in mature mammalia.