Figure 6 | Scientific Reports

Figure 6

From: Predominant synthesis of giant myofibrillar proteins in striated muscles of the long-tailed ground squirrel Urocitellus undulatus during interbout arousal

Figure 6

Ultrastructural organization of longitudinally sectioned m. longissimus dorsi sarcomeres of ground squirrels: representative views. (A) Summer activity, (B) interbout arousal, (C–F) hibernation. S sarcomeres. About one third of muscle fibres of m. longissimus dorsi during torpor represents straight ordered sarcomeric structures. The other two thirds show a disordered sarcomeric structure, with dramatic changes in sarcomeric length (cf. length S on A and C), disordering of myofilament directions (arrowheads on E), disappearance of zones I, A, H and lines M (see C,E,F), dissociation of Z-disk structure (Z on E,F), and detachment of myofilaments from Z-disks (asterisks on D,F) and from one another (arrowheads on D,F). (A,B,C,E) are the central part of the myofibre; (D,F), in close vicinity to myofibres’ plasma membrane. All scale bars, 500 nm.

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