Transverse sarcomere splitting. A possible means of longitudinal growth in crab muscles.
Transversely split sarcomeres are seen in mouthpart muscles of the blue crab in the electron microscope. Sarcomeres split only at the H zone. Two new sarcomeres are formed by a Z disk which appears in the H zone of the splitting sarcomere. Splitting may involve breaking of the thick filaments in the H zone, elongation of these filaments, and formation of both new actin filaments and Z-disk materials, Sarcomere splitting would allow longitudinal growth of muscle cells without lengthening of sarcomeres and concomitant changes in contractile properties.
D000818:Animals; D003386:Brachyura / Q000033:anatomy & histology*; D024510:Muscle Development; D009132:Muscles / Q000648:ultrastructure*; D009210:Myofibrils / Q000648:ultrastructure*