Neonatal hippocampal neurons, retrogradely labeled with granular blue, survive intracerebral grafting and explantation to tissue culture.

Previous studies have shown that developing neocortical neurons labeled in situ by retrograde axonal transport of the fluorescent dye Granular Blue can retain this dye for at least 2 months essentially without fading or leakage. In this study, retrograde labeling with Granular Blue was used to label neonatal rat hippocampal neurons prior to intracerebral grafting to uninjected littermates, and explantation as slice cultures. Hippocampal regio inferior and hilar neurons labeled through their developing commissural axons were found to survive axotomy and subsequent grafting and explantation for at least 3 and 8 weeks, respectively. The labeling helped define the developmental differentiation of the neurons at the time of manipulation and provides a new method for identification of a specific population of transplanted or explanted neurons.