Figure 1: Morphological changes in HDFs in culture (a). Senescence-associated β-galactosidase staining. Positive blue stains of SA β-gal appeared in SIPS and control senescent HDFs as indicated by arrows. Micrographs are shown at 100x magnification (b). Quantitative analysis of positive β-galactosidase stained cells (c). Data are expressed as means SD, . adenotes compared to control young.