Defining Microglial Phenotypic Diversity and the Impact of Ageing

.....................................................................................................................VII LIST OF FIGURES ....................................................................................................... XVII LIST OF TABLES ........................................................................................................ XXIII LIST OF ABBREVIATIONS....................................................................................... XXV Introduction ...................................................................................................... 1 Chapter 1: Background........................................................................................................... 1 1.1 Glial cells of the CNS ......................................................................................... 2 1.2 Astrocytes .................................................................................................. 3 1.2.1 Oligodendrocytes ..................................................................................... 5 1.2.2 Ependymal cells ........................................................................................ 6 1.2.3 Microglia ............................................................................................................... 7 1.3 Origin of microglia ................................................................................... 7 1.3.1 Important growth factors for microglial development ........................ 9 1.3.2 Microglia in the healthy brain ............................................................... 10 1.3.3 Microglial-astrocytic communication .................................................. 11 1.3.4 Microglial-neuronal communication.................................................... 12 1.3.5 Microglial-synapse interaction .............................................................. 14 1.3.6 Microglial phagocytic receptors ............................................................ 17 1.3.7 Microglia activation ................................................................................ 20 1.3.8 Heterogeneity of microglial cells .................................................................... 26 1.4 Region-dependent properties of the CNS............................................ 26 1.4.1 Current evidence for microglial heterogeneity ................................... 26 1.4.2 Ageing ................................................................................................................. 27 1.5 The ageing CNS ...................................................................................... 28 1.5.1