Synaptic covering obtained by a detailed analysis of inputs in apposition to the surface of sciatic motoneurons. (A) Percentage of absolute retraction of nerve terminals from apposition to the postsynaptic membrane in the different mice strains. One week after axotomy, a significant loss of covering can be seen in iNOS-/- mice as compared to C57BL6/J mice. (B - D) Percentage of synaptic covering by F-, S- and C-terminals on the unlesioned and lesioned sides. Note that after injury the iNOS-/- mice presented a greater loss of F- type terminals than the WT mice. * = p < 0.05 and ** = p < 0.01 (Mann-Whitney U test).