Structure of motor nerve terminals in chickens with hereditary muscular dystrophy

The structure and size of 1-week to 1-year-old normal (line 412) and dystrophic (line 413) chicken motor nerve terminals were studied using combined pre- and postsynaptic histologic endplate staining. The main result is that adult dystrophic terminals have abnormal structure and are significantly smaller than normal. These differences occurred progressively during development. At 1 week ex ovo, dystrophic motor nerve terminals were similar to normals in size and appearance. By 8 weeks, differences between normal and dystrophic terminal size and structural organization began to emerge. Qualitatively, beginning at 8 weeks and becoming more frequent by 1 year of age (the endpoint of this study), dystrophic motor endplates differed from normal in having: generally smaller synaptic boutons, often separated by extremely thin branching interconnectives; increasing incidence of multiple innervation; and frequent occurrences of apparent partial or total denervation, terminal sprouting, and reinnervation.