Fine structure of the drum muscles of the piranha (serrasalminae, characidae).
The anterior and the posterior drum muscles of the piranha resemble each other in all essential fine structural aspects: myofibrils are slender; sarcomeres are short compared with those of other drum muscles; mitochondria, located in the periphery of the fibers, are numerous and show an irregular internal structure; and the sarcoplasmic reticulum is abundant. Triads appear at the level of the Z lines. The drum muscles have many motor endplates, which, however, lack the characteristic junctional-fold apparatus. No lipid substances could be demonstrated in these muscles. In the posterior drum muscle the fibers depart from their orderly longitudinal arrangement at irregular intervals.
D000818:Animals; D005399:Fishes / Q000033:anatomy & histology*; D006003:Glycogen / Q000032:analysis; D008055:Lipids / Q000032:analysis; D008931:Mitochondria, Muscle; D009045:Motor Endplate; D009132:Muscles / Q000032:analysis / Q000648:ultrastructure*; D009210:Myofibrils; D012519:Sarcoplasmic Reticulum; D014831:Voice
D008055:Lipids; D006003:Glycogen