Previous work reported increases in the number of myelinated axons in the s
plenium of the rat corpus callosum between 25 and 60 days of age. In the pr
esent study, we quantified the area occupied by myelinated axons using a li
ght microscopic point counting technique at 60, 120 and 180 days. Myelinate
d axons increased across these ages (p = 0.001). Thus, myelination of the r
at corpus callosum persists well into adulthood. (C) 2000 Elsevier Science
B.V. All rights reserved.