FIGURE 2.

Asymmetric stem cell self‐renewal divisions are decreased, and symmetric stem cell self‐renewal divisions are increased, in aged versus adult human keratinocytes. (a) Illustration showing asymmetric and symmetric SC self‐renewal divisions, as well as a symmetric differentiation division in human keratinocytes. Scale bars 10 µm. (b) Methods used to analyze SC division fate of the first division after plating. (c) Immunofluorescence studies for keratin 1 and Numb expression. Representative asymmetric and symmetric SC self‐renewal divisions and symmetric differentiation division in human keratinocytes. Scale bars 10 µm. (d) The total number of SC self‐renewal divisions was decreased in aged versus adult keratinocytes. (e) The number of asymmetric SC self‐renewal divisions was decreased in aged versus adult keratinocytes. (f) The number of symmetric SC self‐renewal divisions was increased in aged versus adult keratinocytes. (g) The proportion of asymmetric SC self‐renewal divisions was decreased and (h) the proportion of symmetric SC self‐renewal divisions was increased in aged versus adult keratinocytes. (i) Pie charts showing proportions of asymmetric and symmetric SC self‐renewal divisions from g and h. Values are expressed as mean ± SEM and analyzed using a Student's t test. *p < 0.05, **p < 0.01