Quantitative histological findings in the sural nerves of neonates.

The quantitative histological study was achieved on the sural nerves obtained at autopsy from three neonates without neurological disorders. The distributions of the myelinated fiber diameters were unimodal and the peaks of the size frequency distributions were at 2-3 microns. These findings coincide with those for children under two years of age, and the latter dose with those for children over 2 months old and adults reported up to now. There were many smaller myelinated fibers under 4 microns in the neonates in comparison with in the children over 2 years old or adults. The densities were higher than those for children over 2 months old, and the ratio of unmyelinated to myelinated fibers was approximately twice as large as that in the children over 2 years old.