Ultrastructure of the myocardial cell and its membrane systems in the adult fly Calliphora erythrocephala (Insecta: Diptera) |
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Authors: | Dr Helge Jensen |
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Institution: | (1) Cellular Cardiology Research Group, Institute of Anatomy, University of Bergen, Norway;(2) Institute of Anatomy, Årstadveien 19, N-5000 Bergen, Norway |
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Abstract: | Summary
Calliphora erythrocephala has cross-striated cardiac muscle cells with A, I and Z-bands. The diameters of the myosin and actin filaments are 200–250 Å and 85 Å respectively and the length of the myosin filaments (A-band) is approximately 1.5 . Usually 8–10 actin filaments surround each myosin filament.The myocardial cells show a well-developed membrane system and interior couplings. A perforated sheet of SR envelopes the myofibrils at the A-band, dilates into flattened cisternae at both A-I band levels before it merges into a three-dimensional net-work between the actin filaments of the I-bands and between the dense bodies of the discontinuous Z-discs. The T-system consists of broad flattened tubules running between the myofibrils at the A-I band levels forming dyads with the SR-cisternae. Longitudinal connections between the transverse (T-) tubules often occur.It is suggested that this well-developed SR may be an adaptation to facilitate a rapid contraction/relaxation frequency by an effective Ca2+ uptake. |
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Keywords: | Cardiovascular system Insecta (Calliphora erythrocephala) Myofibrils Sarcoplasmic reticulum |
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