Figure 3.

Representative photographs of a TUNEL assay in rat NSCs. Only a few TUNEL-positive cells were observed in the control culture (A). However, numerous darkly stained TUNEL-positive cells indicating enhanced apoptosis were observed in Ag-NP-exposed culture (B). Quantification [by counting the number of positively-stained cells in five 0.24 mm² field (one in the center and one in each of the four corners Wang et al., 2005)] shows a significantly increased number of TUNEL-positive cells in Ag-NP-exposed cultures compared with the controls (C). Data are presented as means ± SDs. **** P < 0.0001. Scale bar = 50 μm.