Effect of denervation on limb growth

Abstract

This study used Rana pipiens tadpoles to assess the effect of complete and partial sciatic denervation on tibial bone growth and foot growth. Complete sciatic denervation was performed in R. pipiens at Stages XIV, XVII, and XX and they were killed at Stages XVII, XX, and XXIV. Partial denervation consisted of peroneal or tibial nerve sectioning at Stages XVII and XX with killing at Stages XX and XXIV. Analysis of experimental animals and controls consisted of (a) quantitative axon counts, (b) tibial length, (c) midtibial cross-sectional area, (d) midtibial cortical thickness, (e) midtibial cartilage anlage cross-sectional area, (f) foot silhouette area, and (g) osteocyte number and osteocyte density. Both complete and partial denervation resulted in significant effects on bone and foot growth: (a) decreased bone length, (b) decreased cross-sectional bone area without cortical thinning, (c) increased cartilage anlage cross-sectional area, and (d) decreased foot size. This experiment demonstrated a trophic effect of nerve on bone growth and development and foot growth. The mechanism of this action is unknown but the data suggests a slowed rate of maturation in denervated bones. The possibility exists that defective peripheral nerve–limb tissue interactions may cause human deformities such as idiopathic clubfoot and idiopathic limb length discrepancy.