Abstract
Body muscle cells of the bloodworm Glycera, a polychaete annelid, were studied by electron microscopy and compared with muscle cells of the more slowly acting nematode Ascaris, which have been described previously. Both muscles are obliquely striated. The predominant type of bloodworm fiber is characterized by a prominent transversely oriented sarcoplasmic reticulum with numerous dyads at the surface of each cell. Thick myofilaments are ∼3 µ long and overlap along ∼60% of their length in extended fibers and ∼80% in shortened fibers. There is virtually no endomysium and very little intracellular skeleton, and the cells are attached by desmosomes to one another rather than to connective tissue. Dense bodies are absent from the fibers and in their place are Z lines, which are truly linear rather than planar. Scattered among the predominant fibers are others, less orderly in arrangement, in which the SR is much less prominent and in which the thick filaments are thicker and longer and overlap to an even smaller degree. It is suggested that physiological differences between bloodworm and Ascaris muscles derive from differences in the proportion of series to parallel linkages between the contractile elements, differences in the amount and disposition of the SR, and differences in the impedance to shear within the myofibrils.
Full Text
The Full Text of this article is available as a PDF (2.0 MB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Bárány M., Bárány K., Gaetjens E., Bailin G. Chicken gizzard myosin. Arch Biochem Biophys. 1966 Jan;113(1):205–222. doi: 10.1016/0003-9861(66)90175-5. [DOI] [PubMed] [Google Scholar]
- FAWCETT D. W., REVEL J. P. The sarcoplasmic reticulum of a fast-acting fish muscle. J Biophys Biochem Cytol. 1961 Aug;10(4):89–109. doi: 10.1083/jcb.10.4.89. [DOI] [PMC free article] [PubMed] [Google Scholar]
- FRANZINI-ARMSTRONG C., PORTER K. R. SARCOLEMMAL INVAGINATIONS CONSTITUTING THE T SYSTEM IN FISH MUSCLE FIBERS. J Cell Biol. 1964 Sep;22:675–696. doi: 10.1083/jcb.22.3.675. [DOI] [PMC free article] [PubMed] [Google Scholar]
- HANSON J. The structure of the smooth muscle fibres in the body wall of the earth worm. J Biophys Biochem Cytol. 1957 Jan 25;3(1):111–122. doi: 10.1083/jcb.3.1.111. [DOI] [PMC free article] [PubMed] [Google Scholar]
- HUXLEY A. F., NIEDERGERKE R. Structural changes in muscle during contraction; interference microscopy of living muscle fibres. Nature. 1954 May 22;173(4412):971–973. doi: 10.1038/173971a0. [DOI] [PubMed] [Google Scholar]
- HUXLEY H., HANSON J. Changes in the cross-striations of muscle during contraction and stretch and their structural interpretation. Nature. 1954 May 22;173(4412):973–976. doi: 10.1038/173973a0. [DOI] [PubMed] [Google Scholar]
- Hess A. The sarcoplasmic reticulum, the T system, and the motor terminals of slow and twitch muscle fibers in the garter snake. J Cell Biol. 1965 Aug;26(2):467–476. doi: 10.1083/jcb.26.2.467. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Heumann H. G., Zebe E. Uber Feinbau und Funktionsweise der Fasern aus dem Hautmuskelschlauch des Regenwurms, Lumbricus terrestris L. Z Zellforsch Mikrosk Anat. 1967;78(1):131–150. [PubMed] [Google Scholar]
- LUFT J. H. Improvements in epoxy resin embedding methods. J Biophys Biochem Cytol. 1961 Feb;9:409–414. doi: 10.1083/jcb.9.2.409. [DOI] [PMC free article] [PubMed] [Google Scholar]
- PORTER K. R., PALADE G. E. Studies on the endoplasmic reticulum. III. Its form and distribution in striated muscle cells. J Biophys Biochem Cytol. 1957 Mar 25;3(2):269–300. doi: 10.1083/jcb.3.2.269. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Page S. G. A comparison of the fine structures of frog slow and twitch muscle fibers. J Cell Biol. 1965 Aug;26(2):477–497. doi: 10.1083/jcb.26.2.477. [DOI] [PMC free article] [PubMed] [Google Scholar]
- RICHARDSON K. C. The fine structure of autonomic nerve endings in smooth muscle of the rat vas deferens. J Anat. 1962 Oct;96:427–442. [PMC free article] [PubMed] [Google Scholar]
- ROSENBLUTH J. SMOOTH MUSCLE: AN ULTRASTRUCTURAL BASIS FOR THE DYNAMIC OF ITS CONTRACTION. Science. 1965 Jun 4;148(3675):1337–1339. doi: 10.1126/science.148.3675.1337. [DOI] [PubMed] [Google Scholar]
- Rosenbluth J. Obliquely striated muscle. 3. Contraction mechanism of Ascaris body muscle. J Cell Biol. 1967 Jul;34(1):15–33. doi: 10.1083/jcb.34.1.15. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Rosenbluth J. Ultrastructural organization of obliquely striated muscle fibers in Ascaris lumbricoides. J Cell Biol. 1965 Jun;25(3):495–515. doi: 10.1083/jcb.25.3.495. [DOI] [PMC free article] [PubMed] [Google Scholar]