MUTUAL INTERACTION BETWEEN HOST AND GRAFT TISSUES IN EMBRYONIC NEURALTRANSPLANTATION

THE differentiation of AChE-positive cells in embryonic neural grafts from various brain regions into the hippocampus after fimbria-fornix t ransection was investigated. Rat fetal cell suspensions of basal foreb rain, hippocampus, mesencephalon or cortex were prepared from fetuses of either embryonic day 14 (E14) or day 19 (E19) gestational age, and these were transplanted into the rat brain after unilateral fimbria-fo rnix transection. Dense acetylcholinesterase (AChE) positive fibres we re observed in both E14 and E19 basal forebrain grafts. These fibres w ere also found in E14 hippocampal grafts. However E19 hippocampal graf ts did not have any AChE-positive fibres. These results suggest that E 14 hippocampal grafts might be affected by the host brain tissues and differentiate into cholinergic neurones.