TABLE 1.
Counts of Muscle Spindles in a Proximal (GL) and a Distal (MG) Muscle of Mutant and WT Mice at P7–P21a
| Spindle counts | % of WT | % myoNT3 | |
|---|---|---|---|
| A. GL muscle | |||
| WT | 35.5 ± 0.3 (4) | — | — |
| myoNT3 | 47.3 ± 0.9 (3)* | 133% | — |
| Er81−/− | 3.5 ± 0.4 (8)* | 9.8% | — |
| myoNT3;Er81−/− | 86.7 ± 2.8 (10)*,b,c | 252% | 189% |
| B.MG muscle | |||
| WT | 10.2 ± 0.3 (6) | — | — |
| myoNT3 | 30.3 ± 0.7 (8)* | 297% | — |
| Er81−/− | 18.5 ± 0.6 (6)* | 181% | — |
| myoNT3;Er81−/− | 50.5 ± 2.9 (8)*,b,c | 495% | 167% |
a
Note that the introduction of the myoNT3 transgene results in the formation of supernumerary spindles and that this effect is augmented by the absence of ER81 (myoNT3;Er81−/−double mutants). Spindle counts are expressed as mean ± SEM (N). Groups denoted an asterisk are significantly different from wild-type at P < 0.05.
b
A significant difference from myoNT3 at P < 0.05.
c
A significant difference from Er81−/− at P < 0.05.
GL, gluteus; MG, medial gastrocnemius; WT, wild-type; P, postnatal day; NT3, neurotrophin-3.