Hippocampal neurons grafted to newborn rats establish efferent commissural connections.

The formation of commissural projections from developing rat hippocampal neurons grafted to the hippocampus of newborn littermates was examined by retrograde axonal transport of the fluorescent dye Fluorogold (FG). At six weeks of age the recipients received two injections of FG in the hippocampus contralateral to the graft. This resulted in labelling of normal, commissurally projecting neurons in the dentate hilus and CA3 of the host hippocampus. Neurons in several transplants were also labelled, and based on morphology and location they were identified as CA3 and dentate hilus neurons.