Preservation of three-dimensional capillary structure in frog muscle during aestivation.

In mammals, prolonged immobilization of the limbs can result in a loss of capillary tortuosity, resulting in skeletal muscle haemorrhaging if rapid remobilization is permitted. In this study, we examined the effect of 4 months' immobilization on semimembranosus capillary structure in the Green-striped burrowing frog, Cyclorana alboguttata. C. alboguttata routinely aestivates as part of a physiological strategy to avoid desiccation in semi-arid environments and, in this capacity, the hindlimbs of C. alboguttata are immobilized in a cocoon for months at a time. We found that 4 months' aestivation had no effect on three-dimensional capillary structure in the semimembranosus muscle and that capillary tortuosity is preserved in immobilized C. alboguttata. The preservation of capillary structure in the hindlimb muscles of C. alboguttata in part accounts for their remarkable ability to emerge with a fully competent locomotor system after prolonged immobilization.