(G) Z-disc intervals (sarcomere length) of slow skeletal muscle at 1 dpf in smyhc1+/+ (n = 380), smyhc1R673H/+ (n = 293), and smyhc1R673H/R673H (n = 268). Distance between z-discs was measured in anti-α-actinin stained slow skeletal muscle fluorescence images. The central bands of the boxplots represent the median, the boxes of the boxplots represent the interquartile range (between the first and third quartile), and the whiskers represent the minimum and maximum values, up to 1.5 times the interquartile range. Outliers displayed are outside of this range. (H) Z-disc intervals (sarcomere length) of slow skeletal muscle at 3 dpf in smyhc1+/+ (n = 249), smyhc1-/- (n = 278), smyhc1R673H/+ (n = 246), and smyhc1R673H/R673H (n = 252). The central bands of the boxplots represent the median, the boxes of the boxplots represent the interquartile range (between the first and third quartile), and the whiskers represent the minimum and maximum values, up to 1.5 times the interquartile range. Outliers displayed are outside of this range. 