Morphometric analysis of sciatic nerve and its main branches in the rabbit.

In the rabbit the myelinated fibres with the largest diameter originating from the sciatic nerve distribute mainly into the peroneal nerve, even though there is no difference in the density of myelinated fibres of the representative unit between the sciatic nerve and its branches. The distribution of the myelinated fibre diameters is unimodal in the sciatic nerve, but bimodal both in the peroneal and tibial nerves. The quotient axon diameter/fiber diameter (g ratio) shows a different trend between the sciatic nerve and the branches originating from it. Except for the peroneal nerve, the increase of the axon calibre corresponds to the reduction of the relative myelin sheath thickness and therefore to the reduction of internodal distance. The results show that the sciatic nerve and its terminal branches in the rabbit have morphometrical characteristics that are peculiar and differ from those of the other rodents.