LIST OF FIGURES Figure Page 2-1 Chamber used for immunomagnetic separations... 13 2-2 Cell isolation in methylcellulose 21 2-3 A2B5 antigen modulation in vitro 25 2-4 In vitro development of A2B5( + ) cells 27 2-5 A2B5 antigen modulation via methylcellulose... 30 2-6 Calculated incomplete separations 33 2-7 Remixed separated cells 35 2-8 Effects of substrata: glass vs polyornithine.. 38 2-9 Neurofilament expression in vitro 43 2-10 GS expression in vitro 47 2-11 3H-thymidine incorporation into monolayers.... 51 2-12 Summary diagram of results 53 3-1 Markers for dissociated cells (graph) 78 3-2 Markers for dissociated cells (photos) 80 3-3 A2B5 antigen modulation in vitro 85 3-4 In vitro development of A2B5( + ) cells 89 3-5 Filament expression in vitro 93 3-6 Oligodendrocyte development in vitro 97 3-7 3H-thymidine incorporation into monolayers .... 101 3-8 Summary diagram of results 104 vii