Architectural and fiber type distribution considerations relative to repeated biopsies in Rhesus monkey hindlimb muscles

The feasibility of performing reliable, repeated needle biopsies in the soleus (Sol), medial gastrocnemius (MG) and tibialis anterior (TA) muscles in the Rhesus monkey was assessed. Muscles from three adult monkeys were prepared for histochemical analysis and fibers were qualitatively typed as fast-twitch glycolytic (FG), fast-twitch oxidative glycolytic (FOG) and slow-twitch (SO). For the Sol and MG within an animal, the fiber type distributions of the approximate biopsy sites at three levels along the proximo-distal axis were similar, while the TA showed more variability. Fiber type data from post-mortem needle biopsies (ranging between 100 to 400 fibers) from selected muscle regions in two monkeys were consistent with data from the cross-sections. Muscles from two other monkeys were prepared for gross architectural determinations. Fiber length to muscle length ratios were approximately 0.24, 0.27 and 0.32 for the Sol, MG and TA, respectively, indicating that multiple biopsies could be taken along the same muscle surface without the risk of sampling the same fibers twice. Together, these data indicate that it is possible to obtain consistent, repeated biopsies from the Sol, MG and, most likely, TA muscles of the Rhesus monkey.