Research Paper Volume 15, Issue 5 pp 1306—1329

Figure 2. Muscle fiber size increase in aged C57BL/6 mice with AAV1.NT-3 gene therapy. (A) Succinic dehydrogenase (SDH)-stained skeletal muscle showing muscle fiber types based on mitochondria content and angular atrophic type 2 fibers (arrows). Dark (D) fibers are fatigue-resistant slow twitch oxidative (STO) or type1 fibers, intermediate (I)-stained fibers are fast twitch oxidative (FTO/type 2A) fibers, and light (L) fibers are fast twitch glycolytic (FTG/type 2B). Representative images from (B) tibialis anterior and (C) gastrocnemius muscles showing three different zones (deep, intermediate, and superficial; designated as Zone 1, 2, and 3) from the untreated (UT) and NT-3 treated cohorts. Scale bar = 30 μm.