FIGURE 4. Total number of 
-cells increases with age.
From the following article:
Adult pancreatic 
-cells are formed by self-duplication rather than stem-cell differentiation
Yuval Dor, Juliana Brown, Olga I. Martinez and Douglas A. Melton
Nature 429, 41-46(6 May 2004)
doi:10.1038/nature02520
Representative flow cytometric analysis of dissociated mouse pancreases stained for insulin expression. Shown are 0.1% of total pancreatic cells (a, b, 3-month-old nulliparous ICR female, 19,379 cells shown; c, 14-month-old nulliparous ICR female, 114,087 cells shown). a, No anti-insulin antibody added. The x axis is CY5 fluorescence (reflecting insulin staining); the y axis is autofluorescence. Insets, insulin-positive -cells.
