title: A histochemical, morphometric and ultrastructural study of gastrocnemius and soleus muscle fiber type composition in male and female rats.
abstract: The fiber type composition of gastrocnemius and soleus muscles of adult male and female rats was examined by histochemical, morphometric and ultrastructural methods. Six male and 6 female, 3.5-month-old rats were used in the study. The fiber types were determined using the adenosine triphosphatase (ATPase) and succinate dehydrogenase (SDHase) staining techniques. The number of fibers of different types and the diameters of these two muscles were examined by morphometric methods. Gastrocnemius muscles were also examined by transmission electron microscopy. Z-line thickness, actin length, sarcomere length and M-line thickness of the fiber types were compared at the ultrastructural level. No significant differences were observed between the diameters of the gastrocnemius muscle (p > 0.05) of male and female rats although the male animals were significantly larger than the females (p > 0.05). In males, type I fibers of the gastrocnemius were larger than in females (p < 0.05). Region II of the gastrocnemius muscles of females contained more type IIA and type IIB fibers than in males. Sarcomere lengths were also longer in females (p < 0.05). The composition of fiber types of gastrocnemius and soleus muscles may be sex dependent.
authors.affiliation: Department of Histology and Embryology, Faculty of Medicine, Akdeniz University, Arapsuyu, Antalya, Turkey. ustunel@hipokrat.med.akdeniz.edu.tr
authors.forename: I
authors.initials: I
authors.lastname: Ustunel
authors.forename: R
authors.initials: R
authors.lastname: Demir
mesh_terms: D000818:Animals; D048429:Cell Size; D005260:Female; D006651:Histocytochemistry; D008297:Male; D008853:Microscopy; D008854:Microscopy, Electron; D018485:Muscle Fibers, Skeletal / Q000145:classification / Q000166:cytology* / Q000648:ultrastructure*; D018482:Muscle, Skeletal / Q000033:anatomy & histology* / Q000166:cytology / Q000648:ultrastructure*; D051381:Rats; D012737:Sex Factors