Histomorphology of rabbit thigh muscles: establishment of standard controlvalues

The thigh muscles of New Zealand White (NZW) rabbits are frequently used in experimental surgery, particularly for evaluation after reinnervation or i schaemia. Although histomorphometric analyses are regularly performed, morp hological data for untreated thigh muscles in previously unoperated animals are not available. Specimens from the rectus femoris (RF), vastus medialis (VM) and adductor magnus (AM) muscles from both thighs were harvested in 7 untreated rabbits and were processed for histomorphometric evaluation. The right RF and VM were harvested in a further 5 rabbit hindlimbs after exper imental denervation and reinnervation of the contralateral RF and subsequen tly processed for histomorphometric analysis. Muscle fibre type distributio n, diameter and connective tissue content were evaluated on serial transver se cryosections reacted for ATPase and NADH tetrazolium reductase activity and statistical analysis was performed. In all untreated animals RF reveale d the highest proportion of type I muscle fibres (right: 8.4+/-4%, left: 11 .4+/-4.9%), whereas VM showed the highest percentage of IIa fibres (right: 31.9+/-5.5%, left: 28.3+/-7.8%) and AM the highest proportion of IIb/d fibr es (right: 80.5+/-5.6%, left: 84.4+/- 6.3%). Fibre type distribution and di ameter in rabbits after contralateral experimental operations revealed a st atistically significant difference from the data obtained in bilaterally un treated animals. Knowledge of the morphology of untreated muscles is fundam ental to the understanding of changes induced by intervention to the ipsi a nd/or contralateral thigh muscles.