Figure 1. Identification of mosaic vessels in primary metastatic breast cancer tumors.

(A-B) 2D images of a mosaic vessel (A) and a fully lined vessel (B) in primary tumors from an orthotopic transplant of ROSA^mTmG; MMTV-PyMT tumor organoids into non-fluorescent NSG host mice, stained with CD31 (green), collagen IV (white) and DAPI. Arrowheads mark gaps in basement membrane. Scale bars: 30 μm in (A) and 50 μm in (B). (C-D) 2D images of a mosaic vessel (C) and a fully lined vessel (D) in human breast tumors stained with actin (red), CD31 (green), collagen IV (white) and DAPI. Arrowheads mark gaps in basement membrane. Scale bars: 30 μm in (C) and 50 μm in (D). (E) Measurements of average distance of mosaic vessel to tumor-stroma border and the average radius of each analyzed tumor. (F) Probability density function of distance of mosaic vessels to the tumor-stroma border, normalized to tumor radius. Represents 60, 168, and 103 mosaic vessels for early murine, late murine tumors, and human primary tumors. At least 6 tissue slides were analyzed per tumor across 3 independent experiments per condition. Normalized measure ranges between 0 (at tumor-stroma border) and 100 (center of tumor). Median normalized distance of mosaic vessels to the tumor-stroma border was 17, 6, and 13 for late stage, early stage and human tumors, respectively.