Figure 4

Proportion of stem/progenitor cells in mammary epithelium unchanged in parous compared with age-matched virgin tissue. (a) Flow cytometry plot of cells isolated from age-matched virgin (AMV) tissue and stained with anti-CD24 and anti-Sca-1 antibodies showing a typical gate used to isolate total mammary epithelial cells for transplantation. This gate was based on the data obtained from the lentiviral transduction experiments, which demonstrated that the CD24^+/Low Sca-1^- plus the total CD24^+/High regions defined the entire mammary epithelium. (b) to (d) Carmine stained whole mounts showing examples of (b) large ductal outgrowths, (c) small ductal outgrowths and (d) an alveolar structure generated by transplantation. Arrow, region enlarged in the inset. Bar = 4 mm. (e) Table of results of limiting dilution transplants indicating the number of outgrowths obtained and the number of fat pads transplanted for each cell dilution. The extent to which each outgrowth filled the host fat pad is indicated by the symbols below the numbers. Data are from seven independent cell isolation and transplant sessions.