Prolonged survival and trophic function of neurons in homologous transplants of sensory ganglion in vivo

Abstract

Neurons in gustatory ganglia which survive autologous transplanatation in vivo retain their trophic effectiveness and can cause taste bud regeneration. In the present study homologous ganglion transplanatation in vivo was performed to see if these neurons would also survive and induce bud regeneration. The vagus nodose ganglion was transplanted in adult male rats and, 30 weeks later, studied for the presence of neurons, the nerves for nerve fiber growth, and the tongue's vallate papilla for taste buds. A small number of neurons was found in all nine transplanted ganglia; these neurons appeared morphologically and histochemically normal. Furthermore, some of these surviving neurons gave rise to nerve fibers which caused taste bud regeneration; after removal of the ganglion these buds degenerated. A mild cellular reaction consisting of large-nucleated cells, neutrophilic leucocytes, and small lymphocytes was present around but not within the transplanted ganglia and its nerve fibers; a cellular reaction was not seen in the papilla. The results demonstrate that neurons can survive homologous transplantation in vivo and still perform a trophic function, and it therefore seems that neurons may not evoke, or be adversly affected, by an immune reaction.