Mitchell J A, Hepburn H R, Heffron J J
Cytobiologie. 1978 Apr;16(3):444-50.
The flight-related tergo-coxal muscles of flying and flightless beetles are compared. In the flying beetle, Pachynoda sinuata, the myofibrils and cylindrical and the myofilaments packed in double hexagonal arrays. The sarcomeres are short (2.8 micrometer) and wide with many large, closely packed adjacent mitochondria but the sarcoplasmic reticulum is poorly developed in this fibrillar (asynchronous) muscle. Sarcoplasmic glycogen in rosette form is abundant. In the flightless beetle, Anthia thoracica, the myofibrils are lamellar-like with sarcomeres of 5.3 micrometer. The myosin filaments form a single hexagonal array each thick filament having an orbital of 11 to 12 thin filaments. The width of the Z-line (120 nm) of A. thoracia muscle was twice that of the Z-line of P. sinuata muscle. The sarcoplasmic reticulum and T-system are well-developed in this afibrillar (synchronous) muscle. Few glycogen granules are present. Triangular projections of the sarcolemma occur regularly opposite the Z-lines in A. thoracica and they appear to extend into the Z-lines. Membranous connections joint adjacent Z-lines in A. thoracica and occasionally in P. sinuata.
对飞行甲虫和不能飞的甲虫中与飞行相关的背基节肌进行了比较。在飞行甲虫中华厚缘步甲（Pachynoda sinuata）中，肌原纤维呈圆柱形，肌丝排列成双重六边形阵列。肌节短（2.8微米）且宽，有许多紧密排列的大型相邻线粒体，但在这种纤维状（非同步）肌肉中肌质网发育不良。呈玫瑰花结形式的肌质糖原丰富。在不能飞的甲虫胸斑扁甲（Anthia thoracica）中，肌原纤维呈片状，肌节长5.3微米。肌球蛋白丝形成单一六边形阵列，每条粗丝有11至12条细丝的轨道。胸斑扁甲肌肉的Z线宽度（120纳米）是中华厚缘步甲肌肉Z线宽度的两倍。在这种无纤维状（同步）肌肉中，肌质网和T系统发育良好。糖原颗粒很少。在胸斑扁甲中，肌膜的三角形突起在Z线相对处规则出现，并且似乎延伸到Z线中。膜性连接在胸斑扁甲中连接相邻的Z线，在中华厚缘步甲中偶尔也会出现。
