title: Differences of morphometrical parameters in hind limb muscle fibres between ovarectomized and sexually intact female dogs.
abstract: Slow and fast twitch fibres of the Mm. tibialis cranialis, semitendinosus and sartorius of seven sexually intact and seven ovarectomized female beagles were histochemically and morphometrically analysed. Along with type I and type IIA fibres, another main type II fibre (IIS), which seems to be peculiar to the dog, was found in the Mm. semitendinosus and tibialis cranialis. Type I fibers comprised 26% and type II fibres 74% of all recorded muscle fibres in the M. tibialis cranialis, 29% (type I) and 71% (type II) in the M. semitendinosus and 51% (type I) and 49% (type II) in the M. sartorius, respectively. The average single profile area and the corresponding mean diameter of fibre types I and II in the investigated hind limb muscles were generally larger in ovarectomized than in sexually intact animals. This was more evident in type II than in type I fibres. However only the type II fibres of the M. tibialis cranialis and sartorius exhibited a statistically significant increase in diameter (p < 0.01 and p < 0.05, respectively). Accordingly, the mean density (number of fibres/mm2) of both fibre types in the hind limb muscles of spayed dogs was generally reduced. Again, this reduction attained statistical relevance in the type I and II fibres of the tibialis cranialis. In addition, the fibre densities of type I in the semitendinosus and type II in the sartorius muscles were also significantly reduced in ovarectomized dogs. In conclusion, ovarectomized beagles showed a generally increased mean diameter of the investigated type I and II hind limb muscle fibres and a concomitant decreased average fibre density of the respective types when compared to sexually intact animals.
authors.affiliation: Institute of Veterinary Anatomy, Faculty of Veterinary Medicine, University of Zürich, Switzerland. hgeyer@vetanat.unizh.ch
authors.forename: Cornelia
authors.initials: C
authors.lastname: Z'berg
authors.forename: Heinz R
authors.initials: HR
authors.lastname: Augsburger
mesh_terms: D000251:Adenosine Triphosphatases / Q000032:analysis; D000818:Animals; D004285:Dogs; D005260:Female; D006614:Hindlimb; D018656:Muscle Fibers, Fast-Twitch / Q000166:cytology*; D018657:Muscle Fibers, Slow-Twitch / Q000166:cytology*; D018482:Muscle, Skeletal / Q000166:cytology*; D010052:Ovariectomy; D012016:Reference Values
chemical_list: D000251:Adenosine Triphosphatases