Figure 2. Isolated cells remain in a progenitor state during the proliferation phase.

Neurospheres during proliferation (after 7 days of culture; A–E) and after another week under differentiation conditions (A′–E′). While only few cells under proliferation conditions stain positive for neuronal (A,B), glial (C,D) and muscular markers a considerable number of cells express these markers after another week of differentiation (A′–E′).