One biopsy specimen was obtained from the treated preauricular area of each patient at each time point, ie, before laser treatment, immediately after laser treatment, and at days 30 and 90 after laser treatment, for a total of 4 biopsy specimens per patient. The biopsy site was anesthetized with 1% lidocaine with 1:100000 epinephrine, and a 1.25-mm punch biopsy specimen was obtained using a metal hair transplant punch. After the punch had been inserted to the level of the subcutaneous fat, the punch was withdrawn, leaving a cylindrical column of tissue attached by a pedicle. The pedicle was cut with curved iris scissors, and hemostasis was achieved with pressure or 35% aluminum chloride solution. Each specimen was divided into 2 or 3 small pieces before fixation. Tissue specimens were fixed in 1.6% glutaraldehyde in 0.1-mol/L Sorensen buffer at a pH of 7.3 (98 mL of 27.22-g potassium phosphate per liter of distilled water plus 102 mL of 28.39-g sodium phosphate per liter of distilled water) for 20 minutes. The fixative was then replaced by 0.1-mol/L Sorensen buffer at a pH of 7.3 for 3 rinses of 20 minutes each. The samples were placed into microcentrifuge tubes with positive sealing lids (snap caps) (Eppendorf tubes, Brinkmann, Westbury, NY) filled with Sorensen buffer at a pH of 7.3 and mailed (via Federal Express) to France on ice blocks. The tissue was then postfixed in 1% osmium tetroxide, dehydrated through a graded ethanol series, and embedded in epoxy resin (Epon). Thin sections were cut on an ultramicrotome (Nova microtome, LKB-Produktter AB, Bromma, Sweden), double stained with uranyl acetate–lead citrate, and observed in a transmission electron microscope (Elmiskop I, Siemens Corp, Iselin, NJ).