Cortical transplants reveal CNS trophic interactions in situ.

Five days after transplanting fetal rat posterior cortex into newborn host rats with posterior cortex lesions, the host's dorsal lateral geniculate nucleus (dLGN) contains 2-5 times as many neurons as the dLGN of lesion-only controls. This effect is temporary and restricted to neurons created later in dLGN neurogenesis. Similar transplants of cerebellar plate are ineffective. These findings suggest that intracranial transplants of CNS tissue can be a source of specific trophic support to particular host neurons.