to prove that such axonal regrowth from spinal and brain stem nerve cells did originate from injury of central nerve fibres innervating the graft and not by sprouting from undamaged c.n.s . neurons at both ends of the 'bridge ' , we first labelled with the fluorescent dye fast blue ( fb ) the cells whose axons were interrupted by the crush and , after two weeks , applied a second dye , nuclear yellow ( ny ) 1 cm beyond the site of injury .
C0027882
neurons
C0004461
axons