MKI67 and hydrops fetalis: To reconcile the different hair coat phenotypes of Scd1−/− mice and Lgr5‐Cre;Scd1fl/fl mice, we evaluated the proliferation and apoptosis of the cells in hair bulb to understand the effect of SCD1 on growth and regression of HFSCs, respectively.[24] Surprisingly, in Scd1−/− mice, although there are elongated HFs, the number of Ki67+ proliferating cells and apoptotic cells in hair bulbs were comparable to those in WT mice (Figure 2H–J), suggesting that the HF defects observed may be indirect effects.