Sarcomagenesis and myofibril maturation during limb regeneration and development of the newt, Triturus alpestris and salamander, Salamandra salamandra.
During limb regeneration of the salamander, Salamandra salamandra, muscles dedifferentiate and then  mesenchymal cells appear, which subsequently, differentiate into muscle. Both in regenerates and in developing limbs of newts larvae mesenchymal cells begin to differentiate into myoblasts, which contain both thin (7 nm) and thick (14 nm) filaments, which are often associated with microtubules, developing a cytoskeletal network, which contribute directly to the shape of myoblasts and a linear alignment of the myofibrils. Both thin and thick filaments appear as a tandem near the periphery of the myoblasts, where myofibrilogenesis occurs. In the early stage of sarcomagenesis the appearance of "Z-bodies" was observed. They were intimately associated with the tandem of filaments thus forming the primary sarcomere units. Consequently the "Z-bodies" coalesce to form primitive Z-lines. The maturation of the primary sarcomeres occurs during fibrilogenesis and is manifested by the gradual thining of the Z-line and thickening of the M-line.
D000818:Animals; D002454:Cell Differentiation; D003599:Cytoskeleton / Q000648:ultrastructure; D008854:Microscopy, Electron; D008870:Microtubules / Q000648:ultrastructure; D009132:Muscles / Q000166:cytology* / Q000502:physiology; D009210:Myofibrils / Q000648:ultrastructure*; D012038:Regeneration; D012454:Salamandra; D014319:Triturus