Fine structural study of the abdominal muscle receptor organs of the crayfish (Procambarus clarkii). Fast and slow receptor muscles

摘要: Abstract Receptor muscles of the abdominal muscle receptor organs crayfish, Procambarus clarkii , were examined by electron microscopy. Both fast and slow strand comprises a single fibre which is divided invagination cell membrane into numerous cytoplasmic processes in its intermediate region (the so-called intercalated tendon). Most these myofibrillar insert this region, but some them pass through without interruption join other portion fibre. Thus muscles, whilst maintaining continuity throughout their whole length, are modified regions, becoming fasciculated providing spaces occupied connective tissue dendrites sensory neurone. Clear-cut differences fine structure shown between two types unit. The shows typical features arthropod including short sarcomere length (on average 3.3 μm), cylindrical myofibrils, well-developed sarcoplasmic reticulum, regular hexagonal array myofilaments. By contrast, characterized long sarcomeres (average 6.5 μm) unique organization myofilaments, with very thick ‘thick’ filaments having diameters range 25–36 nm surrounded about 12 thin filaments.