The aim of the study was to compare the mice-recipient's brain tissue cell-structural reactions in response to intracerebral implantation of syngeneic and allogeneic cell suspensions of neural progenitor cells (NPC) (E13-15). The NPC suspensions from mice-donors of C57BL/6 and CBA containing 72.7 +/- 9.9% Vimentin+ and 81, 812, 5% GFAP+ cells were inoculated by standard procedure in right temporal segment of cerebral hemisphere of mice-recipients C57BL/6 (1 x 10(6) cells per animal). The certain part of mice-recipients of allogeneic NPC were immunosupressed by Sandimmune (100 mkg per animal) on day 0, 3, 6 after neurotransplantation. The standard histological preparations of mice brains were performed after 24 hours, 6, 12, 18 and 37 days after NPC neurotransplantation, which were investigated by cytoanalyzer "IBAS" (Germany). After intracerebral inoculation of allogeneic foetal NPC the signs of the pericellular edema and lymphocyte infiltration were detected in adjacent brain sections on day 12-18 and decreased on day 37. Allogeneic foetal NPC were reserved till day 18 and revealed the signs of primary differentiation. After immunosupression by "Sandimmune" the foetal NPC underwent the phoenotypic differentiation and infiltration in related brain sections. On the day 37 the implanted NPC were not detected. Focal reaction of the brain glial component to implanted NPC declined faster after syngeneic NPC neuroimplantation (up to day 18) than after allogeneic NPC neuroimplantation (up to day 37). After the syngeneic NPC inoculation on the 37th day at the site of implantation the formation of a small fragment of immature bone was fixed, which may indicate the possibility of NPC transdifferentiation in other cell types.