ULTRASTRUCTURE OF HEART-MUSCLE CELLS OF CUTTLEFISH ROSSIA-MACROSOMA (DELLE CHIAJE) (MOLLUSCA-CEPHALOPODA)

  • 1 January 1977
    • journal article
    • research article
    • Vol. 185  (2) , 147-158
Abstract
The muscle cells of the ventricle, the branchial heart and the branchial heart appendages of R. macrosoma are studied. The ventricle myocardium has 3 muscle layers, while the other 2 organs exhibit a loose arrangement of muscle cells. The muscle cells of the ventricle, the branchial heart and the branchial heart appendages are similar in structure. The nuclei are surrounded by myofibrils. In the myofibrils A-, I- and discontinuous Z-bands are seen. The diameters of the thick filaments are 300-400 .ANG., their length varies from 1.7-3.9 .mu.. Thin filaments have a diameter of approximately 85 .ANG.. The ratio between thick and thin filaments is roughly 1:11. The SR [sarcoplasmic reticulum] runs mostly as a longitudinal network within the myofibrils. A few short T-tubules are observed in the Z-regions. Peripheral and internal couplings exist. The latter are few in number. Intercalated discs are small and rarely observed. They were found in all 3 organs. A difference in the function of these organs is not reflected in the ultrastructure of the intercalated discs. These discs are often of the interdigitating type with interfibrillar junctions and unspecialized regions. Peripheral couplings are seen at the unspecialized regions. The intercalar surfaces of the muscle cells shoulder off into the lateral surface, and the transition between the 2 surfaces is not sharp. Attachment plaques are found scattered over the whole sarcolemma.