Table 1

Semiquantitative evaluation of the fast to slow twitch transition

Stage of muscle fiber

Fiber

Type II

Type I

Cytoplasmic

Fiber size

(myotube) differentiation

Type^a

staining^b

staining

p27

1 - resting fast (young)

fast

+++

-

-

normal

2 - transitory 1

trans 1

+++

++

-

normal or increased

3 - transitory 2

trans 2

++

+++

+

normal or increased

4 - transitory 3

trans 3

-

+++

++

normal or increased

5 - resting slow (mature)

slow

-

+++

-

normal

6 - early deg (aging)

deg 1–2

-

+++

++

normal

7 - late deg (regressing)

deg 3–4

-

+++

+++

fragmented

^a fast = fast twitch fibers; trans 1 = early, trans 2 = mid, trans 3 = late transition of fast- to slow twitch fibers; slow = slow twitch fibers; deg 1–2 = early, deg 3–4 = advanced degeneration (shrinking and fragmentation; see Fig. 3, D-F for examples, and Fig. 6 for staging). ^b Semiquantitative grading: -, none; +, weak; ++, moderate; +++, strong (see Fig. 3 to 6 for corresponding densities).

Bukovsky et al. BMC Clinical Pathology 2001 1:4   doi:10.1186/1472-6890-1-4