Abstract
Electron microscopy of thin sections of muscle fibers in myotomes of Amblystoma larvae has revealed the presence of a complex, membrane-limited system of canaliculi and vesicles which form a lace-like reticulum around and among the myofibrils. This seems to correspond to the sarcoplasmic reticulum of the earlier light microscopists and the endoplasmic reticulum of other cell types. The elements constituting the reticulum are disposed in a pattern which bears a constant relation to the bands of the adjacent myofibrils and is therefore repeated in each sarcomere. At the H band the system is transversely continuous but not so at other levels. Longitudinally continuity is interrupted at the Z bands where large vesicles belonging to adjacent sarcomere segments of the system face off on opposite sides of the band. The opposing faces of these vesicles are flat and separated by a space of more or less constant width, in which are located small, finger-shaped vesicles. In view of these and other close structural relationships with the myofibrils it seems appropriate to assign to the system a role in the conduction of the excitatory impulse.
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Selected References
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- BENNETT H. S., PORTER K. R. An electron microscope study of sectioned breast muscle of the domestic fowl. Am J Anat. 1953 Jul;93(1):61–105. doi: 10.1002/aja.1000930104. [DOI] [PubMed] [Google Scholar]
- PALADE G. E. A small particulate component of the cytoplasm. J Biophys Biochem Cytol. 1955 Jan;1(1):59–68. doi: 10.1083/jcb.1.1.59. [DOI] [PMC free article] [PubMed] [Google Scholar]
- PALADE G. E. Studies on the endoplasmic reticulum. II. Simple dispositions in cells in situ. J Biophys Biochem Cytol. 1955 Nov 25;1(6):567–582. doi: 10.1083/jcb.1.6.567. [DOI] [PMC free article] [PubMed] [Google Scholar]
- PORTER K. R. Electron microscopy of basophilic components of cytoplasm. J Histochem Cytochem. 1954 Sep;2(5):346–375. doi: 10.1177/2.5.346. [DOI] [PubMed] [Google Scholar]
- PORTER K. R. The fine structure of cells. Fed Proc. 1955 Sep;14(3):673–682. [PubMed] [Google Scholar]
- WATSON M. L. The use of carbon films to support tissue sections for electron microscopy. J Biophys Biochem Cytol. 1955 Mar;1(2):183–184. doi: 10.1083/jcb.1.2.183. [DOI] [PMC free article] [PubMed] [Google Scholar]