Fig. 5

Early lesions in mCol1a1 recipients display invasive protrusions that contain aligned collagen fibers. a Hematoxylin/eosin stain (H&E) of tumor cell line (TC)2 tumors (left panels) at 17 days, TC4 tumors (right panels) at 24 days after transplantation. b Tumor edges (H&E). Arrowheads indicate finger-like protrusions into the mammary fat pad. c Higher magnification of boxed area from (b). d Picrosirius red staining. Note yellow-orange fibers in the protrusions in mCol1a1 tumors. Original magnification × 100. a, b, d, scale bars = 100 μm. e Second harmonic generation (SHG) imaging of collagen fibers. Yellow dashed lines indicate tumor boundaries. *Indicates adjacent fat pad. Representative images × 400 magnification. Scale bars = 50 μm. f CurveAlign analysis of relative collagen alignment following CT-FIRE fiber extraction as described in “Methods”. 0 = perfectly random fibers, 1 = perfectly aligned fibers. Mean ± SEM, n = 4 tumors of each cell line/host genotype combination, 7–9 images per tumor. Repeated measures, group comparison, SAS Proc Mixed model. *p < 0.05, ****p < 0.001. WT wild-type