a, Schematic of MeSC behaviour during the hair cycle. b, Hair greying after mice were subjected to chronic unpredictable stress. Quantifications were done by plucking around 100 hairs from different regions across the skin and counting the number of white hairs (n = 9 plucked regions from 3 mice for each condition, two-tailed unpaired t-test). c, Hair greying after mice were subjected to restraint stress. Quantifications as described in b. d, LC–MS/MS quantification of corticosterone and noradrenaline after restraint stress (n = 5 mice for control and n = 6 mice for restraint, two-tailed unpaired t-test). e, Left, immunofluorescent staining of hair bulbs for melanocyte-inducing transcription factor (MITF, red) from mice five days after treatment with saline or RTX. Right, quantification of MITF+ cells (n = 30 hair follicles from 3 mice for each condition, two-tailed unpaired t-test). f, Fontana-Masson staining of hair bulbs for melanin from mice five days after treatment with saline or RTX (n = 6 mice for each condition). g, Coat colour in mice five days after RTX injection in anagen. RTX was injected in full anagen and the mice were examined five days later, at late anagen. The coat colour remained black (n = 6 mice for each condition). h, Fontana-Masson staining of hair follicles for melanin from mice that were treated with saline or RTX at first anagen and examined at second anagen (see Fig. 1e for corresponding fluorescent images) (n = 6 mice for each condition). i, Quantification of the number of MeSCs in the skin of mice injected with saline or RTX. For the RTX-injected mice, the numbers of MeSCs in regions with predominantly black hairs and regions with many white hairs are quantified separately. Orange and green dashed boxes denote representative black and white hair regions, respectively, in RTX-injected mice. Enlarged boxes show representative immunofluorescent images of hair follicles from each region. White arrowheads indicate regions where MeSCs reside (n = 30 hair follicles from 3 mice for each condition, one-way ANOVA with Tukey’s multiple comparisons test). j, Quantification of the body area covered by white hairs in female versus male mice (n = 5 mice for each sex, two-tailed unpaired t-test). All data are mean ± s.d. Source data