Table 1.
The size of synaptic AChR clusters, the density of synaptic AChRs, as well as the elimination of synapses are normal in CD24 mutant mice
| CD24−/− | Wild type | |
|---|---|---|
| Size of synaptic AChR clusters | 442 ± 23 μm3 | 406 ± 19 μm3 |
| 543 ± 27 μm3 | 464 ± 23 μm3 | |
| AChR density | 492 ± 14 | 489 ± 16 |
| 524 ± 17 | 487 ± 13 | |
| Multiply innervated synapses | 5.6% (6/108) | 6.3% (6/95) |
| 6.7% (10/149) | 6.0% (7/116) |
Whole mounts of diaphragm muscles from wild-type and CD24 mutant mice, at P11, were stained with antibodies to neurofilament and synaptophysin and Alexa 594–α-BGT. Three-dimensional reconstructions of image stacks were analyzed to measure the size of synaptic AChR clusters (number of voxels) and the average density of AChRs within these clusters (total grayscale value/number of voxels). We measured synaptic size and AChR density at ≥25 synapses in two mice from each genotype; the mean ± SEM in each mouse is indicated. The extent of polyneural innervation was measured by rotating three-dimensional reconstructions and counting the number of axons that project into individual synaptic sites (Movies 1 and 2). We calculated the extent of polyneuronal innervation at ≥95 synapses in two mice from each genotype; the percentage of synaptic sites that were multiply innervated in each mouse is indicated.