COEXPRESSION OF MAP-2 AND GFAP IN CELLS DEVELOPING FROM RAT ECF RESPONSIVE PRECURSOR CELLS

In this study we have performed a detailed analysis of EGF-responsive precursors as they develop into neurons and astrocytes using antibodie s to nestin, microtubule-associated protein 2 (MAP-2c and MAP-2ab) and glial fibriallary acidic protein (GFAP). Surprisingly, at early time points, most GFAP-positive cells also stained for MAP-2c, and we postu late that this may be a normal stage of astroglial development. At 7 d ays most of the cells had developed into astrocytes and MAP-2ab-positi ve cells only represented 5% of the total neuronal population. This st udy shows that (i) MAP-2c is a marker for early precursors, (ii) the m ajority of cells developing from EGF-responsive precursors develop int o glia and (iii) only a small population of cells arising from expande d populations of EGF-responsive precursors develop into neurons expres sing MAP-2ab. Thus, certain critical signals important for full neuron al differentiation may be missing from this system.