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Ultrastructural alterations in extrinsic eye muscles induced by vincristine
Abstract:
A comparative morphological analysis of the effects of vincristine on particular types of muscle fibres of the eye and selected trunk muscles of the mouse was performed. Great resistance of the mouse organism to the action of sublethal doses of vincristine has been found. Degenerative changes of great intensity (atrophy of myofibrils, disturbances of the Z line) and the appearance of new changes, not mentioned hitherto among the vincristine myopathies (megamitochondria, intermembranous inclusions, glycogen in mitochondria and very large vacuoles) were observed in the trunk muscles of mice. The eye muscles are seem to be more resistant to the action of vincristine. The intensity of changes in the eye muscles was connected with the types of muscle fibres. Red fibres, rich in mitochondria, underwent relatively greatest changes, whereas the smallest changes were found in tonic fibres, poor in mitochondria and sarcotubular system, i.e. these structures from which spheromembranous bodies, most characteristic of the pathogenic effects of vincristine arise.
Insights
Mice showed high resistance to vincristine. Trunk muscles experienced severe damage, including novel changes, while eye muscles, particularly red fibers, were more affected than tonic fibers.
Area of Science:
- * Pharmacology
- * Cell Biology
- * Neuroscience
Background:
- * Vincristine is a chemotherapy drug with known neurotoxic effects.
- * Previous studies have documented vincristine-induced myopathies, primarily in skeletal muscles.
Purpose of the Study:
- * To comparatively analyze the morphological effects of vincristine on different muscle fiber types in mouse eye and trunk muscles.
- * To identify novel ultrastructural changes induced by vincristine exposure.
Main Methods:
- * Comparative morphological analysis of muscle tissues from mice treated with vincristine.
- * Light and electron microscopy to examine cellular and subcellular alterations.
Main Results:
- * Mice exhibited significant resistance to sublethal doses of vincristine.
- * Trunk muscles showed intense degenerative changes (myofibril atrophy, Z-line disturbances) and novel alterations (megamitochondria, inclusions, glycogen in mitochondria, large vacuoles).
- * Eye muscles were more resistant; changes correlated with fiber type, with red fibers (mitochondria-rich) showing greater damage than tonic fibers (mitochondria-poor).
Conclusions:
- * Vincristine induces distinct myopathic changes in mouse trunk and eye muscles.
- * Muscle fiber type influences susceptibility to vincristine-induced damage, with mitochondria-rich fibers being more vulnerable.
- * Novel ultrastructural findings expand the understanding of vincristine's pathogenic mechanisms.