Comment on "Human Neuroblasts Migrate to the Olfactory Bulb via a Lateral Ventricular Extension"

Curtis et al. (Research Articles, 2 March 2007, p. 1243) claimed discovery of a human neuronal migratory stream to the olfactory bulb along a putative lateral ventricular extension. However, high levels of proliferation reported with proliferating cell nuclear antigen were not confirmed using different markers, neuronal chain migration was not demonstrated, and no serial reconstruction shows a true ventricular extension.