Fp and Fr in Skin Aging Figure 4. Evolution with age of Fp and Fr morphology. Fp and Fr samples from 3 young donors (19 yr, 21 yr, and 26 yr) and 3 old donors (57 yr, 62 yr, and 74 yr) were examined by flow cytometry according to the morphological parameters of size (forward scatter, FSC) and granularity (side scatter, SSC). FSC versus SSC dot plots corresponding to a typical pair of young [19 yr] Fp (A) and Fr (B), and a typical pair of old [74 yr] Fp (C) and Fr (D). Median FSC and SSC values were determined for the different samples. (E) Comparison of Fp and Fr FSC values in young and old donors (mean6SEM, n = 3). (F) Comparison of Fp and Fr SSC values in young and old donors (mean6SEM) (*p,0.05; n.s. = not significant). a.u. = arbitrary unit. doi:10.1371/journal.pone.0004066.g004 PLoS ONE | www.plosone.org 7 December 2008 | Volume 3 | Issue 12 | e4066