Minimal connectivity between six month neostriatal transplants and the host substantia nigra.

The present study sought to determine if axonal connectivity is established between 6-month-old neostriatal transplants and the host substantia nigra. Cell suspensions of fetal neostriatum were transplanted into the adult rat neostriatum lesioned previously by kainic acid. Horseradish peroxidase injections into the ipsilateral ventral midbrain labelled the lesion site and the intact neostriatum extensively, but no appreciable anterograde or retrograde label was found within the graft. These results demonstrate a paucity of connectivity between neostriatal grafts and the host brain at a time when other investigators have described transplant-mediated recovery of function.