Successful transplantation of the fetal brain tissue into a resection cavity on the motor cortex area of young, adult and aging host brain is described. These studies explored the survival, growth and viability of the grafts from E12, E15 and E18 rats fetal frontal cortex (door and host wistar rat). Animals were prepared for light microscope (Nissl Golei)2, 4 and 6 months later .Implants by both fetal tissues had a 80% survival rate. In motor cortex of the host brain, the younger the fetal implant, the higher the success of the implant, but the most successful implants were the E15 (E15>E12>E18) . For the speed of the growth the E12 is the fastest (E12>E15>E18).The implants not only increased in mass (up to 6—7 fold in most of cases at 4 months) but differentiated and matured neurons were observed one to two months postimplantation.Implants were easily identified in all cases on the basis of cellular organization and the presence of a neuron sparse Zone present at the borders, just like the molecular layer of the normal cortex.There was no apparent difference in the size or organization of implants examined 4 moths after implantation as compared with those examined after longer survival times. Golgi staining demonstrated that both pyramidal and nonpyramidal cells were in the grafts. No preferential positioning or lamination of these different cells were seen with respect to each other, although some pyramidal cells had apical dendrites oriented toward "molecular zones" . These had the most recognizable pyramidal morphology, although pyramidal cells through the graft had many typical aspects of pyramidal cells such as large "apical" dendrites and spines.Nonpyramidal cells were of two types spiny and aspiny.
