Table 1.
Morphological features of sternomastoid NMJs in aged mice
| Feature | Frequency | % of NMJs |
|---|---|---|
| Fragmentation | 118/142 | 83.1 |
| Dim AChR patches | 7/132 | 5.3 |
| Aneural AChR patches | 20/132 | 15.2 |
| Preterminal axonal swelling | 18/125 | 14.4 |
| Polyneuronal innervation | 9/139 | 6.5 |
| Terminal sprouts | 7/135 | 5.2 |
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Sternomastoid muscles from four animals 22–26 months of age were analyzed for features previously shown to occur at aging NMJs (Valdez et al., 2010). An endplate was considered fragmented if it had 10 or more discrete AChR-rich segments/islands. The 142 NMJs had an average of 15.1 ± 0.5 fragments. There appeared to be no gender-based disparity for fragmentation (83.3% of NMJs in males vs 83.0% of junctions in females had 10 or more fragments).
