Apoptosis

In order to identify the potential follicular targets for laser action and to define the onset of laser-induced apoptosis, Terminal deoxynucleotidyl Transferase dUTP Nick End Label­ing (TUNEL) staining can be performed to localize apoptotic cells in the irradiated hair follicles. TUNEL is the most commonly used method, which identifies apoptotic cells in situ by labeling of apoptosis-induced DNA fragmentation. Because the melanocytes are known to be the primary target for the laser, double immunostaining for simultaneous detection of apoptotic cells by TUNEL and melanocytes immediately after laser exposure could provide information on the depth of laser penetration and effectiveness of the laser for melanocyte damage (Fig. 9.5). The melanocytes can be visualized histochemically by using the antibody against pMel-17 protein that allows identification of both bulb and scat­tered melanocytes in the outer root sheath at any hair follicle stage [80].