Reduction of Post-lesional Atrophy by Transplants of Fetal Cerebral Cortical Tissue. Host-Transplant Nerve Connections and Trophic Factors
Fetal neocortex grafted into neocortical lesion cavities made in newborn rats has been found to ameliorate cortical lesion-induced thalamic atrophy (Haun and Cunningham 1984; Sharp and Gonzalez 1986b; Sørensen et al., 1989a). Neocortical grafts were also found to reduce the basal forebrain neuronal atrophy that occurs after excitotoxic lesions in adult rats (Sofroniew et al., 1986). This effect of neural transplants on reducing host neuronal atrophy is likely related to the formation of host-transplant nerve connections. In this report, we examine this hypothesis by reviewing recent findings on the apparent trophic effects of cortical transplants on subcortical structures. In particular, we have examined the effect of homo- and heterotopic cortical grafts placed into frontal cortical lesions made in the newborn rat. Our analysis of the relatively discrete thalamocortical projection system in this experimental paradigm is compared to the trophic effects exerted on the more diffuse cholinergic projection system by neocortical transplants placed into adult host cortical lesion cavities.
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