Yannick Bailly was born in 1956. During his PhD at the University of Strasbourg, and the University of P. & M. Curie in Paris, he deciphered the fish gill nervous system. Afterwards, at the CNRS in Paris, he greatly improved the understanding of synapse elimination in the developing rodent cerebellum. Since 1994, after returning to Strasbourg as a CNRS Research Director, his laboratory has become renowned for its expertise in ultrastructural neuroanatomy. He is also the Scientific Director of the Electron Microscopy Department of the Plateforme d’Imagerie in vitro of the Institut des Neurosciences Cellulaires et Intégratives. Yannick Bailly has made major contributions concerning the synaptic localization of cardinal molecules involved in major neurodegenerative diseases, such as amyloid precursor proteins and presenilins in Alzheimer’s disease and prion protein. His group has provided valuable insight into neuronal death mechanisms involved in brain pathologies, in particular in prion diseases, reviewed in a chapter of this book.