Fig. 1.

Changes in SA-β-Gal level during senescence of HPMCs. Cells were forced into senescence by serial passaging at 5-day intervals, as described in the Materials and methods. SA-β-Gal was measured in young and senescent (Sen) cells using cytochemistry (a,b) and fluorescence (c), both at pH 6.0. Results are expressed as mean ± S.D. RLU relative light units. Pictures in panel B show a representative result of cytochemical detection of SA-β-Gal (positive cells have the blue precipitate within the cytoplasm); magnification ×40 (c). Experiments were performed on cell cultures derived from 29 different donors. (Color figure online)