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

Adult hippocampal neurogenesis relies on the activation of neural stem cells in the dentate gyrus, their division, and differentiation of their progeny into mature granule neurons. The complex morphology of radial glia-like (RGL) stem cells suggests that these cells establish numerous contacts with the cellular components of the neurogenic niche that may play a crucial role in the regulation of RGL stem cell activity. However, the morphology of RGL stem cells remains poorly described. Here, we used light microscopy and electron microscopy to examine Nestin-GFP transgenic mice and provide a detailed ultrastructural reconstruction analysis of Nestin-GFP-positive RGL cells of the dentate gyrus. We show that their primary processes follow a tortuous path from the subgranular zone through the granule cell layer and ensheathe local synapses and vasculature in the inner molecular layer. They share the ensheathing of synapses and vasculature with astrocytic processes and adhere to the adjacent processes of astrocytes. This extensive interaction of processes with their local environment could allow them to be uniquely receptive to signals from local neurons, glia, and vasculature, which may regulate their fate

Vitrification of Tokuyasu-style immuno-labelled sections for correlative cryo light microscopy and cryo electron tomography

We present an approach for the preparation of immuno-labelled ultrathin sections from cells or tissue that are compatible with both fluorescence and transmission electron microscopy. Our approach is inspired by a method of Sabanay et al. (1991) that is based on the Tokuyasu technique for immunogold labelling of sections from aldehyde-fixed samples. The difference of this method with the original Tokuyasu technique is that the immuno-labelled sections are stabilized in a thin layer of vitreous water by plunge-freezing prior to electron microscopical observation. The vitrification step allows for phase contrast-based imaging at cryogenic conditions. We show that this immuno-labelling method is well-suited for imaging cellular ultrastructure in three dimensions (tomography) at cryogenic conditions, and that fluorescence associated with the sections is retained. This method is a valuable tool for Correlative Light and Electron Microscopy (CLEM), and we refer to this method in combination with CLEM as VOS (vitrification of sections). We provide examples for the application of VOS using dendritic cells and neurons, and show specifically that this method enables the researcher to navigate to lysosomes and synapses. © 2014 Elsevier Inc

Specific disruption of hippocampal mossy fiber synapses in a mouse model of familial Alzheimer's disease

10.1371/journal.pone.0084349PLoS ONE91e8434