Comparative aspects of muscle fiber types in fetuses of the normal and "double-muscled" cattle
Ashmore, C.R.; Parker, W.; Stokes, H.; Doerr, L.
Growth 38(4): 501-506
1974
ISSN/ISBN: 0017-4793 PMID: 4282366 Document Number: 70847
Muscles from normal and 'double-muscled' foetuses were examined. Muscles of 'double-muscled' foetuses were larger in absolute weight and as percentage of body weight and crown-rump length. The cross-sectional diameters of muscle fibres in the two genotypes did not differ. Cytochemical analysis showed the increase in the number of muscle fibres to be of the alpha-type, which in the adult animal corresponds to the fast-twitch type of fibre. In the 'double-muscled' animal many or perhaps all of these extra alpha fibres are transformed into the anaerobic alpha-W type.