Figure 5.

Muscle fibre size 14 days after BaCl₂ injury. (A) Examples of gastrocnemius cross sections of uninjured control muscles of phosphate‐buffered saline (PBS)‐injected mice (14C) or mitochondrial transplant therapy (MTT)‐treated mice (14CM). Examples of muscle cross sections are shown, where injured muscles were allowed to repair for 14 days after systemic PBS sham‐ treatment (14R) and systemic MTT‐treatment (14RM). Fibre type was identified by immunocytochemistry of myosin heavy chains. Type IIA fibres (green), Type IIB fibres (orange/gold), Type IIX fibres (black) and Type I fibres (red). The white bar is 200 μm in length. (B) Mean fibre cross‐sectional area (CSA) was obtained by planimetry from a minimum of 200 Type IIA and 200 Type IIB fibres in control non‐injured muscles and 200 Type IIA and 200 Type IIB fibres in repairing muscles 14 days after the BaCl2 injury. The data are presented as mean ± SD for each animal. Control non‐injured (PBS‐injected) muscles from PBS‐treated (14C) or MTT‐treated mice (14CM). Injured (BaCl₂ injected) muscles from PBS sham‐treated (14R) or MTT‐treated mice (14RM). *Type IIB fibre CSA for 14C was significantly greater than either 14R or 14RM Type IIB fibres at P < 0.05. Type IIB fibre CSA for 14C and 14RM was significantly greater than 14R at P < 0.05. (C–F) Fibre frequency histograms (C,D) and cumulative frequency distributions (E,F) for Type IIA (C,E) and Type IIB (D,F) fibres. (C,D) The corresponding control muscle data for the frequency histograms (14C or 14CM) are represented by shaded bars. The blue line represents data from PBS‐injected mice 14 days post‐injury (14R). The green line represents data from MTT‐injected mice after 14 days of injury (14RM). (E,F) Cumulative frequency distribution for control muscle data (14C, circle or 14CM, inverted triangle). The blue line represents PBS‐injected mice 14 days post‐injury (14R). The green line represents MTT‐injected mice after 14 days of injury (14RM).