Fig. 5

Precancerous changes occur over time in the AI glands. a Representative pictures of H&E-stained sections from GI and AI glands harvested on day 120 postpartum (n = 5 per group, scale bars = 100 μM, upper panels). The marked area in the upper panel is shown at higher magnification in the lower panels (scale bar = 50 μM). The arrows indicate alveolar hyperplasia. b Representative pictures of squamous metaplasia in the AI glands indicated by asterisks (upper panel, n = 5, scale bar = 50 μM), magnified in the lower panels (scale bar = 25 μM). c Bar diagram showing incidences of hyperplasia (black), metaplasia (hatch), and both (black and hatch) in the GI and AI glands, with normal represented in gray. d Representative images of trichrome-stained FFPE sections of GI and AI mammary glands harvested on day 120 postpartum; the percentage of periductal collagen is quantified in the adjacent bar diagram (n = 3, scale bars = 100 μM). e Representative pictures of Ki67-immunostained sections of mammary glands harvested on day 120 postpartum following GI and AI (n = 3, scale bars = 100 μM). Ki67-positive epithelial cells are quantified in the bar diagram. f Representative image of GI and AI mammary gland sections harvested on day 120 postpartum and immunostained for F4/80-positive cells (n = 3, scale bars = 100 μM) and g CD3-positive cells (scale bars = 100 μM). High-magnification pictures are shown in the inset. The bar diagrams show quantitative difference in the expression of the immune markers between the GI and AI glands. Error bars represent standard error of the mean. Linear mixed models were used to calculate significance