Ultrastructural features of the myotendinous junction of the sternomastoid muscle in Wistar rats: From newborn to aging |
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Authors: | Ciena Adriano Polican De Almeida Sonia Regina Yokomizo De Sousa Bolina Cristina De Sousa Bolina-Matos Regina Grassi Rici Rose Eli Da Silva Marcelo Cavenaghi Pereira Miglino Maria Angélica Watanabe Ii-Sei |
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Affiliation: | 1. Department of Anatomy, Institute of Biomedical Sciences‐ICB III, University of S?o Paulo, S?o Paulo, Brazil;2. Department of Surgery, Faculty of Veterinary Medicine and Animal Science, University of S?o Paulo, S?o Paulo, Brazil;3. Department of Morphology and Genetic, Federal University of S?o Paulo, S?o Paulo, Brazil |
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Abstract: | The myotendinous junction (MTJ) is a major area for transmitting force from the skeletal muscle system and acts in joint position and stabilization. This study aimed to use transmission electron microscopy to describe the ultrastructural features of the MTJ of the sternomastoid muscle in Wistar rats from newborn to formation during adulthood and possible changes with aging. Ultrastructural features of the MTJ from the newborn group revealed pattern during development with interactions between muscle cells and extracellular matrix elements with thin folds in the sarcolemma and high cellular activity evidenced through numerous oval mitochondria groupings. The adult group had classical morphological features of the MTJ, with folds in the sarcolemma forming long projections called “finger‐like processes” and sarcoplasmic invaginations. Sarcomeres were aligned in series, showing mitochondria near the Z line in groupings between collagen fiber bundles. The old group had altered “finger‐like processes,” thickened in both levels of sarcoplasmic invaginations and in central connections with the lateral junctions. We conclude that the MTJ undergoes intense activity from newborn to its formation during adulthood. With increasing age, changes to the MTJ were observed in the shapes of the invaginations and “finger‐like processes” due to hypoactivity, potentially compromising force transmission and joint stability. Microsc. Res. Tech. 75:1292–1296, 2012. © 2012 Wiley Periodicals, Inc. |
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Keywords: | myotendinous junction development muscle, skeletal aging transmission electron microscopy |
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