Maturation and fine structure of thalamic reticular neurons transplanted into the adult rat CNS

This work was undertaken to determine whether or not cell suspension transplants provide a promising vehicle for the in vivo study of neuronal development. Cell suspensions of rat fetal tissue that contained both reticular (RT) and ventrobasal primordia were transplanted into the excitotoxically lesioned somatosensory thalamus of adult rats. The fine structure of transplanted GABAergic RT neurons that were identified by immunocytochemistry was investigated 5 days to 7 months following transplantation. The dissociation and transplantation of the tissue results in disruption of the extracellular matrix and alteration of cellular interactions which could introduce major changes in neuronal maturation. Our results show that maturation of transplanted GABAergic RT neurons was comparable to normal and that they were able to establish and receive, with one exception, usual sets of connections. In contrast, disruption of the tissue was responsible for the definitive loss of organotypic characteristics and the emergence of abnormal connections, especially synaptic connections from somatosensory afferents, the functional significance of which will be important to determine.