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Induction of mitochondrial alterations ex vivo in skeletal muscle
1La Trobe University, Department of Human Biosciences, Bundoora Victoria, Australia.
Abstract:
The ultrastructural alterations of mitochondria were studied, following a fixation delay of 45 min, in the normal type II red muscle fibres of pigeon semimetapatagialis muscle. These muscle fibres, were devoid of myofibrillar degeneration; however, their mitochondria showed derangement. The latter included irregular orientation and loss of cristae, and clearing of the matrix. Some mitochondria showed myelin figures of varying complexity in the subsarcolemmal areas as well as in the interior of muscle fibres. These alterations bear striking resemblance to that seen during some lysosomal formation. The significance of these observations is discussed.
Insights
Mitochondria in pigeon red muscle fibers showed significant ultrastructural changes, including loss of cristae and matrix clearing, after a 45-minute fixation delay. These alterations resemble those observed during lysosomal formation.
Area of Science:
- Cell Biology
- Muscle Physiology
- Mitochondrial Research
Background:
- Type II red muscle fibers are crucial for sustained activity.
- Mitochondria are vital for cellular energy production.
- Ultrastructural analysis requires precise fixation techniques.
Purpose of the Study:
- To investigate mitochondrial ultrastructural alterations in pigeon muscle fibers.
- To determine the impact of a 45-minute fixation delay on mitochondrial morphology.
- To compare observed changes with known cellular processes like lysosomal formation.
Main Methods:
- Transmission electron microscopy was used.
- Pigeon semimetapatagialis muscle fibers (type II red) were examined.
- A fixation delay of 45 minutes was applied prior to ultrastructural analysis.
Main Results:
- Mitochondria exhibited derangement, including irregular orientation and loss of cristae.
- Mitochondrial matrix clearing and myelin figure formation were observed.
- No myofibrillar degeneration was noted in the studied muscle fibers.
Conclusions:
- A 45-minute fixation delay induces significant mitochondrial ultrastructural changes in pigeon red muscle fibers.
- Observed mitochondrial alterations share similarities with early stages of lysosomal formation.
- The findings highlight the sensitivity of mitochondrial structure to fixation delays and suggest potential implications for cellular degradation pathways.