Fig. 1

Mouse mammary glands undergoing abrupt involution are histologically different from gradually involuted glands. a Experimental workflow for modeling pregnancy, lactation, and involution in mice. GI gradual involution, AI abrupt involution. b Representative images of H&E-stained mammary gland sections harvested on day 28 (d28), c day 35 (d35), and d day 56 (d56) postpartum, following GI and AI. High-magnification pictures are shown in the inset. (n ≥ 3, scale bar = 100 μM) e Representative images of Ki67-immunostained sections of mammary glands harvested on d28 and d56 following GI and AI (n = 3, scale bar = 100 μM). % Ki67-positive epithelial cells are represented in the bar diagram. f Experimental workflow for modeling multiparity, lactation, and involution in mice. g Representative images of H&E-stained mammary gland sections from GI and AI mice harvested on day 56 postpartum following third pregnancy. The lower panel shows high-magnification picture of the boxed region in the upper panel (n = 4, scale bar = 100 μM). h Representative images of Ki67-immunostained sections of mammary glands from multiparous mice harvested on d56 following third pregnancy (n = 4, scale bar = 100 μM). % Ki67-positive epithelial cells are represented in the bar diagram. Error bars represent standard error of the mean. The linear mixed model was used to calculate significance