Fig. 1.

Embryonic neurospheres contain proliferating neural stem cells (NSCs). The neurospheres were grown under control conditions in serum-free medium containing 4 mg/l folic acid. On the sixth day in culture, the neurospheres were incubated with the proliferation marker 5'bromo-2'deoxyuridine (BrdU) for 24 h. Subsequently they were stained with specific primary antibodies and fluorescent secondary antibodies to detect BrdU and the NSC marker nestin. Shown are fluorescence photomicrographs of cells expressing nestin (red fluorescence, A), BrdU (green, B), and both nestin and BrdU (yellow, C). The original magnification for fluorescence microscopy was ×200.