The numbers of binucleated nerve cells in the rabbit superior cervical ganglionwere investigated.We found that in the neonatal rabbit the binucleated nerve cellsare 31.4% of the total number of nerve cells,and in the 100-day rabbit,thebinucleated nerve cells increase to 41.4%.We infer that the binucleated sympatheticnerve cells are formed either by the fusion of uninucleated sympathetic nerve cellsor by amitosis of the uninucleated cells.