University of Saarland 2 articles published in JoVE Bioengineering Studying the Stoichiometry of Epidermal Growth Factor Receptor in Intact Cells using Correlative Microscopy Diana B. Peckys1, Niels de Jonge1,2 1INM-Leibniz Institute for New Materials, 2Department of Physics, University of Saarland This protocol describes the labeling of epidermal growth factor receptor (EGFR) on COS7 fibroblast cells, and subsequent correlative light- and electron microscopy of whole cells in hydrated state. The label contained fluorescent quantum dots. The protocol can be used to study the stoichiometry of EGFR at the single molecule level. Neuroscience Conditional Genetic Transsynaptic Tracing in the Embryonic Mouse Brain Devesh Kumar1, Ulrich Boehm1 1Department of Pharmacology and Toxicology, University of Saarland School of Medicine Capitalizing on a binary genetic strategy we provide a detailed protocol for neural circuit tracing in mice that express complementary transsynaptic tracers after Cre-mediated recombination. Because cell-specific tracer production is genetically encoded, our experimental approach is suitable to study the formation and maturation of neural circuitry during murine embryonic brain development at a single cell resolution.