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. 2020 Jul 24;11:3722. doi: 10.1038/s41467-020-17579-6

Fig. 2. Sarcomere branching is extensive, but variable across muscle types and developmental stages.

Fig. 2

a 3D rendering of 77 directly connected sarcomeres within the myofibrillar matrix of a cardiac muscle fiber. Individual colors represent different myofibrillar segments linked by branching sarcomeres. b Percentage of myofibrils with at least one branching sarcomere in different muscle fiber types. N values: postnatal early—141 myofibrils, 1796 sarcomeres, 3 muscles, 3 mice; postnatal late—150 myofibrils, 1401 sarcomeres, 3 muscles, 3 mice; fast twitch—468 myofibrils, 7707 sarcomeres, 4 muscles, 3 mice; slow twitch—299 myofibrils, 3990 sarcomeres, 3 muscles, 3 mice; cardiac—344 myofibrils, 4473 sarcomeres, 5 muscles, 5 mice. c Frequency of sarcomere branching across muscle type. N values: postnatal early—141 myofibrils, 1796 sarcomeres, 3 muscles, 3 mice; postnatal late—150 myofibrils, 1401 sarcomeres, 3 muscles, 3 mice; fast twitch—193 myofibrils, 3477 sarcomeres, 4 muscles, 3 mice; slow twitch—110 myofibrils, 1396 sarcomeres, 3 muscles, 3 mice; cardiac—167 myofibrils, 2114 sarcomeres, 5 muscles, 5 mice. d 3D rendering of 43 directly connected sarcomeres within the myofibrillar matrix of a late neonatal (P14) muscle fiber. Individual colors represent different myofibrillar segments linked by branching sarcomeres. Representative of three muscles from three mice. Scale bars, 2 µm. Plus sign (+): Significantly different (one-way ANOVA, P < 0.05) from postnatal early. Asterisk (*): Significantly different from postnatal late. Pound sign (#): Significantly different from slow. Values: mean ± SE.