A) Representative fluorescent images of fascia and B) orientation of collagen fibers in the fascia in 4-, 6-, and 8-week-old no. 4 inguinal mammary glands; n=5 replicates. Scale bars represent 100 μm or 50 μm for insets. C) Low-magnification fluorescent images of collagen in the fascia of a 6-week-old no. 4 inguinal mammary gland. Scale bars represent 2 mm (top) or 500 μm (insets). Representative fluorescent images of a D) cross-section (scale bar 50 μm) and E) different z slices (scale bar 100 μm) through a no. 4 inguinal mammary gland. F) Spearman correlation between global orientation of collagen fibers in the fascia and the mammary epithelium for the same gland; n=1 gland. G) Pearson correlation between the order parameter describing the local orientation of TEBs with respect to collagen fiber orientation in the fascia and the distance of separation between the fascia and the TEB; n=18 and 13 TEBs from thoracic and inguinal glands, respectively. H) Representative fluorescent images of adipocytes in the fat pad of no. 4 inguinal mammary glands. Scale bars represent 100 μm. I) Alignment fraction and J) orientation of adipocyte cell borders. For all fluorescent images in the figure, tissues are stained with Hoechst 33342 to label nuclei (magenta) and an antibody against type I collagen (green). Data are represented as mean ± SD. n.s., not significant. See also Figure S3.