Research Paper Volume 8, Issue 11 pp 2754—2776

Figure 4. Elevated senescent phenotype and inflammatory response in old mammary glands. (a) Venn diagram of differentially expressed genes during aging (by comparing samples from old and young mice) in MaSC-enriched basal spheres and stromal cells annotated with the top 10 enriched biological processes from Database for Annotation, Visualization and Integrated Discovery (DAVID) platform. The p value of each biological process is shown on the right. (b) There was greater expression of p19^ARF and p16^INK4a RNA in old stromal cells (26 mon.) than their younger (4 mon.) counterparts measured with real-time RT-PCR (n = 4). (c) Quantification of cyclooxygenase 2 staining in primary mammary glands from young (4 mon.; n = 6) and old (26 mon.; n = 4) C57BL/6 mice showing higher expression in old glands. The data are presented as percent ductal structures that had positive staining for cyclooxygenase 2 (defined as more than 25% cells stained positive within a particular ductal structure) in one tissue section of each mammary gland. Scale bar, 100 μm. (d) Quantification of macrophage crown-like structure (CLS) in primary mammary glands from young and old C57BL/6 mice showing higher numbers of CLS/cm² in old (26 mon.; n = 7) than young glands (2-4 mon.; n = 8).