Figure 4. Negative controls in which the primary antibodies for Ki67 and Pax6 (b), Chx10 (d) Oct4 (f) were omitted, showed no immune-reactivity. (a, c and e) Nuclei of the cells were stained blue using DAPI; pictures are related to fields b, d and f respectively. (h) Shows a control without both primary and secondary antibodies. Nuclei of the cells were stained blue using DAPI (g) (magnification: ×400). DAPI, diamidino-2-phenylindole.