ABSTRACT
The common peroneal nerve [CPN] motoneurons were localized by horseradish peroxidase neuronal tracing technique. They extended from caudal part of L4 to the caudal part of L6 segments of the spinal cord in monkey [macaca mulatta]. The number and diameters of myelinated fibres in the CPN and its ventral roots, L4, L5 and L6 of the monkey were estimated from the photomicrographic montages of their araldite embedded transverse sections. The mean count of these fibres was 896 in L4, 3228 in L5, 6959 in L6 and 7497 in CPN. The average diameters of myelinated fibres in ventral root measured between 2 and 1 [micro]m and in CPN between 2 and 22 [micro]m. The percentage of myelinated fibres measuring 9 [micro]m and above was 79.1% in L4, 86.7% in L5, 63.4% in L6 and 63.5% in common peroneal nerve