Neurogenic niches in the developing brain. Dividing cells in the subventricular zone are closely associated with blood vessels, and the concept of a neurovascular niche (yellow), which reflects a zone of influence of vascular factors on neural progenitor cells, suggested in the adult and developmental subventricular zone. In early development, the dividing cells in the ventricular zone are not closely associated with the blood vasculature, but may be affected by trophic factors produced in the CSF, and therefore exist in a neuroglial-CSF niche. Cells from the ventricular zone migrate toward the neurovascular niche, before differentiating and migrating to outer cortical layers of the brain.