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. Author manuscript; available in PMC: 2008 May 30.
Published in final edited form as: Annu Rev Cell Dev Biol. 2006;22:339–373. doi: 10.1146/annurev.cellbio.22.010305.104357

Figure 3.

Figure 3

The bulge stem cells (SCs). Bulge (Bu) SCs are more quiescent than are other keratinocytes with proliferative potential in the skin. Tumbar et al. (2004) developed a strategy for conducting fluorescent pulse-chase experiments in mice engineered to express a tetracycline-regulatable H2B-GFP transgene. After labeling all the skin epithelial cells with H2B-GFP, a four-week chase resulted in significant H2B-GFP-label retention only in the bulge (a). Label-retaining cells (LRCs) could be found along the basal layer of cells that express α6β4-integrins, as well as in a suprabasal location within the bulge (b). Bulge SCs express a high level of the cell surface protein CD34, which has been used with α6-integrin to isolate basal and suprabasal bulge cells, using flow cytometry (Blanpain et al. 2004, Trempus et al. 2003). [The approximate fluorescence of the outer root sheath (ORS) and interfollicular epidermis (IFE) cells is also indicated on the FACS profile.] Tissues were counterstained with Dapi (blue) to mark the nuclei. Abbreviations used: Cb, club hair; HF, hair follicle; SG, sebaceous gland.