Fiber size | Large myelinated fiber | Medium myelinated fiber | Small myelinated fiber | Regression coefficient | Intercept | R2 | |||||
---|---|---|---|---|---|---|---|---|---|---|---|
Group | Young (20Â weeks old) | Elderly (90Â weeks old) | Medium myelinated fiber | Elderly (90Â weeks old) | Young (20Â weeks old) | Elderly (90Â weeks old) | Young (20Â weeks old) | Elderly (90Â weeks old) | Young (20Â weeks old) | Elderly (90Â weeks old) | |
Fiber diameter (μm)a,b,c | 7.67 ± 0.54 | 4.42 ± 0.27** | 3.96 ± 0.09 | 2.33 ± 0.09** | 3.12 ± 0.06 | 1.50 ± 0.04** | −2.27 | −1.46 | 9.46 | 5.67 | 0.54 |
Myelin thickness (μm)a,b,c | 1.13 ± 0.06 | 0.81 ± 0.04** | 0.65 ± 0.03 | 0.51 ± 0.01** | 0.50 ± 0.01 | 0.37 ± 0.01** | −0.32 | −0.22 | 1.40 | 1.00 | 0.52 |
Axon diameter (μm)a,b,c | 5.02 ± 0.45 | 2.81 ± 0.21** | 2.23 ± 0.07 | 1.31 ± 0.06** | 1.63 ± 0.05 | 0.76 ± 0.03** | −1.69 | −1.02 | 6.34 | 3.67 | 0.46 |
Myelin perimeter (μm)a,b,c | 21.85 ± 1.76 | 14.08 ± 0.80** | 10.99 ± 0.38 | 7.89 ± 0.22** | 7.69 ± 0.26 | 5.41 ± 0.13** | −6.57 | −4.34 | 26.99 | 17.80 | 0.47 |
Axon perimeter (μm)a,b,c | 16.06 ± 1.40 | 9.29 ± 0.65** | 7.43 ± 0.35 | 4.46 ± 0.19** | 5.63 ± 0.29 | 2.70 ± 0.08** | −5.21 | −3.3 | 20.12 | 12.07 | 0.46 |
G-ratioa | 0.62 ± 0.01 | 0.61 ± 0.01 | 0.56 ± 0.01 | 0.56 ± 0.01 | 0.52 ± 0.01 | 0.51 ± 0.01 | −0.05 | −0.05 | 0.67 | 0.66 | 0.21 |