Fig. 1

PAPP-A sustains an altered collagen phenotype in post-partum mammary glands. a Representative images of Masson’s trichrome collagen stain (blue) on virgin, involuting, or late post-partum mammary glands from non-transgenic and PAPP-A transgenic mice. n = 5 mice per group. Scale bar 100 μm. b Quantification of collagen per epithelial region by Masson’s trichrome stain on non-transgenic and PAPP-A transgenic virgin, involuting, or late post-partum mammary glands from a. n = 5 mice per group, each point represents the average of ten ducts per mouse per time point. Mean ± SEM, unpaired t test with Welch’s correction: **p < 0.005, ***p < 0.0005. c Representative second-harmonic generation (SHG) imaging of collagen on magnified ducts of histological sections of non-transgenic or PAPP-A transgenic virgin, involuting, or late post-partum mammary glands (lower panels). The yellow dotted lines indicate mammary ducts borders; collagen is seen in white. Corresponding regions of interest (ROI) are shown in top panels. n = 5 mice per group. Scale bar 100 μm. d Graph of collagen intensity relative to the distance from the mammary duct borders of SHG images of non-transgenic mammary glands in c. Mean ± SEM. n = 5 mice per group, unpaired t test with Welch’s correction: *p < 0.05. e Graph of collagen intensity relative to the distance from the mammary duct borders of SHG images of PAPP-A transgenic mammary glands in c. Mean ± SEM. n = 5 mice per group. f Quantification of TACS3 per total curvelets analyzed in virgin, involuting, or late post-partum mammary glands of non-transgenic mice using the CurveAlign software. TACS3 characterized as curvelet angles 60–90 relative to the ductal border. n = 5 mice per group. Mean + SEM, unpaired t test with Welch’s correction (comparisons between the TACS3 group only). *p < .05, **p < 0.005. g Quantification of TACS3 per total curvelets analyzed in virgin, involuting, or late post-partum mammary glands of PAPP-A transgenic mice using the CurveAlign software. TACS3 characterized as curvelet angles 60–90 relative to ductal border. n = 5 mice per group. Mean + SEM, unpaired t test with Welch’s correction (comparisons between the TACS3 group only). **p < 0.005