Fine processes of Nestin-GFP–positive radial glia-like stem cells in the adult dentate gyrus ensheathe local synapses and vasculature

Significance A population of adult neural stem cells supplies the dentate gyrus with new neurons that play a role in mechanisms of learning and memory. Radial glia-like stem cells have a unique morphology, including a dense arbor of fine processes that infiltrate the neurogenic niche. Here, we provide what is, to our knowledge, the first detailed ultrastructural description of these processes, and we reveal that these cells establish a variety of contacts with local blood vessels, synapses, and astrocytes. Given that signals derived from neurons, astrocytes, and blood vessels regulate the process of adult neurogenesis, the identification of these contacts provides a structural framework for elucidating the mechanisms by which this regulation occurs. These results contribute to a greater understanding of the adult hippocampal neurogenic niche.