Soma size of substantia nigra neurons increases after a prenatal neocortical lesion in cats

Seeking an explanation for an increase in volume of the caudate nucleus in adult cats that had sustained a fetal unilateral neocortical lesion, we inv estigated possible morphological changes in the reciprocally interconnected substantia nigra. In fetal-lesioned cats the cross-sectional area of neuro nal somata in substantia nigra, pars reticulata was 33% larger than in cont rol cats (P <0.05), while in pars compacta there was a marked tendency to a n increase (25%, P <0.06). This size increase might have caused the surviva l of a larger number of caudate nucleus neurons during development, and thu s contributed to the reported increase in caudate nucleus volume. (C) 2001 Elsevier Science B.V. All rights reserved.