In simple organisms damaged nerves repair themselves readily, but in mammals the growth of axons is inhibited in the scar tissue that forms after injury. In December Experimental Neurology, Dietmar Fischer and colleagues from University of Münster, Germany, show that lens injury releases molecules that can stimulate significant axonal regeneration throughout the optic nerve of adult rats.

Fischer et al. severed the optic nerve and cut the lenses of rats in order to induce secondary cellular cascades, which are known to strongly support the survival of retinal ganglion cells and to promote axonal regeneration. They found that cut axons could regenerate over long distances within the white matter of the adult optic nerve — spanning over 11 mm to the chiasm and between 12 and 15 mm to the thalamus — and could also make synaptic connections within the brain (Exp Neurol 2001, 172:257-272).

"The...