Figure 5
Transcriptome analysis reveals similarities and differences between embryonic and postnatal mammary cell populations. (A) Heatmap and unsupervised cluster analysis of differential gene expression across postnatal mammary epithelial cells (MECs) and mammary primordial populations. Each horizontal line represents a probe set with red indicating high expression and green indicating low expression in the various tissue compartments. (B) Venn diagrams showing the number of shared and unique genes expressed within mammary primordial compartments compared to the three postnatal mouse MEC subpopulations. (C) Arrows indicate cells expressing nuclear Sox9 within the surface and primordial epithelium. Control tissue shows strong nuclear staining in the developing ribs (arrows) and spinal cord (arrowheads). Strong Vimentin expression is observed in the periderm, surface epithelium and mammary mesenchymal cells. Arrow indicates a mammary primordial epithelial cell expressing Vimentin. Most suprabasal cells of the mammary primordial epithelium express E-cadherin; less intense expression is observed in the periderm and surface epithelium above the mammary bud and some suprabasal cells (arrows). Trps1 stain is non-nuclear within the mammary bud epithelium. Vibrissae mesenchyme shows nuclear stain while some non-nuclear staining is observed in the epithelium at E12.5 (Control). Diffuse CD24 is observed in E12.5 mammary mesenchyme. At E16.5, the mammary bud epithelium and some cells within the mammary mesenchyme express CD24 (Control). A few Nestin-expressing cells are observed within both mammary epithelial and mesenchymal primordial cells. Strong Nestin staining is observed in embryonic nerves at E12.5. Some c-Kit positive cells are observed within the mammary bud epithelium and mesenchyme. Positive control is roof of brain ventricle at E12.5. Erbb2 expression is observed in mammary bud epithelial and some mesenchymal cells at E12.5. SMA is observed in a blood vessel (arrow) adjacent to the mammary bud epithelium, which does not express SMA. Both the mammary bud epithelial and mammary mesenchymal cells express Lef1 and CD29. Scale bar is 50 μm. MBE denotes mammary bud epithelium. MM denotes mammary mesenchyme. MP denotes mammary primordium. LumER- denotes luminal estrogen receptor negative. LumER+ denotes luminal estrogen receptor positive.