Fetal mesencephalic neurons survive and extend long axons across peripheral nervous system grafts inserted into the adult rat striatum.

In adult rats whose nigrostriatal dopamine (DA) pathway had been chemically damaged we implanted a fetal mesencephalic graft over the superior colliculus and joined it to the denervated striatum by means of an approximately 2 cm long segment of heterologous sciatic nerve. Monoaminergic neurons within the implant extended axons along the entire length of the nerve bridges and of these fibers extended into the striatum, which is the normal target of nigral projections. Thus, combinations of fetal neuronal and peripheral nervous system grafts can be used in vivo to provide both a source and a substrate for lengthy axonal growth.