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Figure 4 | Breast Cancer Research

Figure 4

From: New insights into lineage restriction of mammary gland epithelium using parity-identified mammary epithelial cells

Figure 4

Parity-identified mammary epithelial cells (PI-MECs) in involuted mammary glands belong to the alveolar progenitor population. (A) The luminal population of mammary epithelial cells (CD24hi CD49flo) is separated into hormone-sensing cells (Sca1hi CD49blo; purple gate) and alveolar progenitor cells (Sca1lo CD49bhi; orange gate). (B) Relative proportions of hormone-sensing (HS) cells and alveolar progenitor cells (Alv) within the luminal population. (C) Analysis of yellow fluorescent protein-negative (YFPneg) (grey) and YFPpos (PI-MEC, green) subpopulations of luminal cells shows that PI-MECs are found mainly in the alveolar progenitor cell population (orange gate). Note that the combined density/contour plot shows the relative distribution of the population on display and therefore the HS population appears larger in (C) than in (A) because the YFPpos population is plotted separately in (C). (D) Distribution of YFPneg cells and YFPpos PI-MECs within populations of HS cells (Sca1hi CD49blo; purple label) and of alveolar progenitor cells (Sca1lo CD49bhi; orange label). (E) Immunofluorescent probing of an involuted mammary section identifies three luminal cell types: HS cells expressing the estrogen receptor alpha (ERα) (red), PI-MECs expressing YFP (green), and luminal cells expressing CK8 (blue) but neither ER nor YFP. Bar is 10 μm. (F) Relative mRNA expression levels of HS cell marker genes ERα and progesterone receptor (PR) and (G) alveolar cell marker genes Elf5 and β-Casein on populations of sorted HS cells (Sca1hiCD49blo) or alveolar progenitor cells (Sca1loCD49bhi) which were separated based on their YFP expression. Error bars indicate standard deviation for four individual mice.

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