Figure 8
Quantitative ultrastructural analyses of the number of synaptic terminals apposed to the surface of motoneurons after axotomy. (A and E) Representative micrographs of the surface of unlesioned motoneurons from C57BL6/J and iNOS-/- mice strains, respectively. One week after peripheral lesion, C57BL6/J mice show a few synaptic terminals detached from the surface of lesioned motoneurons (B). Such detachment occurred to a greater degree in the ventral horn of the iNOS knockout strain (F). Observe the comparatively lower degree of synaptic covering in iNOS-/- mice as compared to C57BL6/J mice. DT = detached terminal, T = apposed terminal, Mt = motoneuron. The black arrows indicate the location of motoneuron membrane surfaces from which synaptic terminals were detached. (C) Graph of the total number of synaptic terminals per 100 ÎĽm of motoneuron membrane in lesioned and unlesioned neurons. Observe that unlesioned iNOS-/- mice show greater synaptic elimination as compared to WT. This difference is even higher after axotomy. (F, G and H) Graphs of F-, S- and C-terminal numbers per 100 ÎĽm of motoneuron membranes, respectively. A greater loss of F-type terminals can be seen one week after axotomy in iNOS-/- mice. * = p < 0.05 and ** = p < 0.01 (Mann-Whitney U test). Scale bar = 1 ÎĽm.