Figure 3: myofibres decline in size in most limb muscles with age.
From: Muscle stem cells contribute to myofibres in sedentary adult mice
(a–g) Representative cross-sections showing outlined laminin+ myofibres in the EDL, TA, gastrocnemius, plantaris, soleus, diaphragm and EOM at 12 and 20 months in control Pax7+/+;RosaDTA/+ mice. Slow MyHCI+ fibres (red) are identified in the (e) soleus and (f) diaphragm. Scale bar, 100 μm for all panels. Histograms generated using MuscleQNT show relative frequency of myofibres sizes in muscles at 12 months (dark blue, n=7 for each muscle) and 20 months (light blue, n=4 for EDL, n=5 for other muscles). Additional histograms for the (e) soleus and (f) diaphragm show relative frequency of fast MyHCI− and slow MyHCI+ myofibres in muscles at 12 and 20 months. Permutation tests were conducted to determine whether counts of myofibres were significantly different in a particular bin between 12- and 20-month-old muscles (see Methods). Black asterisks indicate an empirical P-value of <0.05 and grey asterisks a value of <0.10 (see Methods).
