Fig. 4. Immunostaining of Wt1 (A), TUNEL-labelling of apoptotic cells (B) and Ki-67 staining of proliferating cells (C) in the olfactory epithelium of a wild-type embryo at E18.5 and in age-matched embryos with splice-specific Wt1 defects. The results shown are representative of the more than 20 tissue sections that were obtained from five animals in each group. (B) More TUNEL-positive (apoptotic) cells were present in the olfactory epithelia of embryos with lack of the +KTS isoform than in wild-type and Wt1(-KTS)-deficient mice. (C) The number of Ki-67 positive cells was slightly reduced in mouse embryos with lack of Wt1(+KTS) compared with normal and Wt1(-KTS)-deficient embryos. Scale bars: 100 µm.