Detection of symmetric and asymmetric cell division by daughter pair analysis. Representative photomicrographs illustrating symmetric division (A) and asymmetric division (B) of MEC (insets are higher magnification images of two daughter cells depicted in the panel). C - Treatment of MEC with xanthosine led to an increase in the proportion of cells undergoing symmetric cell division (P < 0.05) (representative data of three independent experiments). D- Increase in telomerase activity per cells in xanthosine-treated culture in comparison to control culture. A representative photomicrographs of FNDC3B immunostaining in xanthosine-treated (E) cultures. F- xanthosine led to an increase in the percentage (mean + SE, n = 3) of FNDC3B (+) cells across different passage (P). Scale bars: (A-B) =50 μm (photographed at 320X); (E) =100 μm (photographed at 200X).