title: The membrane systems of the cardiac muscle cell of Meganychtiphanes norvegica (m. sars), euphauciacea, crustacea.
abstract: The membrane systems of cardiac muscle cells of the euphausiacean Meganychtiphanes norvegica are described. Transverse tubules are found both at the Z-band level (TZ-tubules) and at the H-band level (Th-tubules). Within the sarcomere narrow longitudinal tubules branch off from the TZ-tubules. At the H-band level these tubules expand forming flattened cisternae in dyadic and triadic couplings with the sarcoplasmic reticulum (SR). Adjacent myofibrils are separated by a well developed SR. Modifications of the SR are seen at the H-band level where junctional cisternae are formed.
mesh_terms: D000818:Animals; D003445:Crustacea / Q000166:cytology*; D008566:Membranes; D009206:Myocardium / Q000648:ultrastructure*; D009210:Myofibrils; D012519:Sarcoplasmic Reticulum