Confirmation of the existence of transitory corpus callosum axons in area 17 of neonatal cat: an anterograde tracing study using biotinylated dextran amine.

Corpus callosum (CC) axons in visual cortex were labeled anterogradely by in vivo biotinylated dextran amine (BDA) in neonatal cat at postnatal day (PND) 6, 10 and 15. Labeled CC axons were distributed throughout the visual cortex including medial area 17. The number of CC axons in medial area 17 increased from PND 6 to PND 10, and then decreased from PND 10 to PND 15. At PND 15, few CC axons could be followed into the grey matter in medial area 17. Thus, BDA labels transitory CC axons that extend through all cortical layers in medial area 17, confirming the results revealed by in vitro DiI labeling.