The thigh muscles of New Zealand White (NZW) rabbits are frequently used in experimental surgery,
particularly for evaluation after reinnervation or ischaemia. Although histomorphometric analyses are
regularly performed, morphological 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 experimental
denervation and reinnervation of the contralateral RF and subsequently processed for histomorphometric
analysis. Muscle fibre type distribution, diameter and connective tissue content were evaluated on serial
transverse cryosections reacted for ATPase and NADH tetrazolium reductase activity and statistical analysis
was performed. In all untreated animals RF revealed 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 fibres (right: 80.5±8.6%, left: 84.4±6.3%).
Fibre type distribution and diameter in rabbits after contralateral experimental operations revealed a
statistically significant difference from the data obtained in bilaterally untreated animals. Knowledge of the
morphology of untreated muscles is fundamental to the understanding of changes induced by intervention to
the ipsi and/or contralateral thigh muscles.