Trophic effects of brain areas on the developing cerebral cortex: I. Growth and histological organization of intraocular grafts.
Trophic interactions during development of brain regions were examined in rats using intraocular grafts of central nervous tissue. The increase in volume of transplanted fetal parietal cerebral cortex, as measured through the cornea, was markedly augmented by the presence of several different previously grafted CNS areas such as locus coeruleus, tectum, or cerebral cortex. DNA measurements and histological examinations suggested that this increased volume was due both to hyperplasia and hypertrophy. Previous grafts of iris, in contrast, did not significantly alter the final size of subsequently grafted cortex pieces. Contact between the two transplants was found to be critical in eliciting the trophic response. Growth-stimulated cortical grafts had a better organized cyto-architecture with larger neurons, including typical pyramidal cells, more neuropil, a lower cell density, and a more organotypic distribution of the cell bodies than non-stimulated controls. The experiments thus demonstrate a profound effect of adjacent neural tissue on development of neocortex. It is concluded that trophic interactions upon brain development can be revealed by sequential intraocular grafting.
D000818:Animals; D002540:Cerebral Cortex / Q000032:analysis / Q000196:embryology*; D004247:DNA / Q000032:analysis; D004627:Embryonic Induction; D005260:Female; D005904:Glial Fibrillary Acidic Protein; D007381:Intermediate Filament Proteins / Q000378:metabolism; D008125:Locus Coeruleus / Q000196:embryology*; D010296:Parietal Lobe / Q000196:embryology; D051381:Rats; D011919:Rats, Inbred Strains; D013477:Superior Colliculi / Q000196:embryology*
D005904:Glial Fibrillary Acidic Protein; D007381:Intermediate Filament Proteins; D004247:DNA