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Morphological changes in murine skeletal muscle in response to exercise and mesterolone

Lookup NU author(s): Karina Fontana, Dr Kathryn White, Emeritus Professor John Harris


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Light and electron microscopy and quantitative morphometry were used to determine the effects of exercise and mesterolone on the soleus muscles of mice. Both exercise and mesterolone caused a significant hypertrophy of extrafusal muscle fibres. The hypertrophy of Type I fibres was greater than that of Type II fibres. There was no hyperplasia. Mitochondria were more numerous and larger than in the muscles of sedentary animals. Capillarity increased and small centrally nucleated muscle fibres appeared, usually in small clusters and most often in the muscles of animals exposed to mesterolone. A small proportion of satellite cells exhibited signs of activation but there were more in the muscles of mesterolone-treated animals than after exercise. Muscles from animals that had been both exercised and treated with mesterolone exhibited the largest changes: muscle mass and muscle fibre hypertrophy was greater than in all other groups of animals, capillarity was higher and > 30% of all recognized satellite cells exhibited signs of activation. Groups of small centrally nucleated muscle fibres were commonly seen in these muscles. They appeared to be the result of splits in the form of sprouts from existing muscle fibres. With both exercise and mesterolone, alone or in combination, there was an increase in the proportion of Type I muscle fibres and a decrease in the proportion of Type II.

Publication metadata

Author(s): Fontana K, White KE, Campos GER, da Cruz-Hofling MA, Harris JB

Publication type: Article

Publication status: Published

Journal: Journal of Electron Microscopy

Year: 2010

Volume: 59

Issue: 2

Pages: 153-164

Print publication date: 01/04/2010

ISSN (print): 0022-0744

ISSN (electronic): 1477-9986

Publisher: Oxford University Press


DOI: 10.1093/jmicro/dfp053


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