Figure 2.

Par3 is essential for normal mammary gland development. (A,B) Carmine alum-stained whole-mount images of control mammary glands after 8 wk. Arrowhead in B shows an end bud in the developing gland. Bars, 0.5 mm. (C,D) Carmine alum-stained whole-mount images of shPar3 mammary glands after 8 wk of regeneration. Arrows in D show multiple small independent outgrowths in a single fat pad. The open arrowhead in D shows regions of small disorganized ducts that lack prominent end buds. Bars, 0.5 mm. (E) The percentage of the fat pad filled by control (n = 6) and Par3-depleted (n = 8) mammary glands was quantified. Error bars, SD. (*) P = 0.00004. (F) Distribution of duct diameters in control (n = 6) and Par3-depleted (n = 8) mammary glands. The diameters of all ducts from control and Par3-depleted glands were measured and categorized in 20-μm increments. (G) Distribution of end bud sizes of control and Par3-depleted mammary glands. The diameters of all terminal ends from control and Par3-depleted glands were measured and categorized in 50-μm increments. (H) Tissue sections from control and Par3-depleted glands were stained for cleaved Caspase-3 (red) and Hoechst 33342 (blue). Bars, 20 μm. (I) Quantification of cleaved Caspase-3-positive cells in control ducts (black bar, n = 5), control end buds (gray bar, n = 5), and Par3-depleted (white bar, n = 5) glands. Error bars, SD. (*) P = 0.034 control duct versus control end bud; (**) P = 0.001 shPar3 versus control duct; (**) P = 0.37 shPar3 versus control end bud. (J) Tissue sections from control and Par3-depleted glands were stained for Ki67 (red) and Hoechst 33342 (blue). Bars, 20 μm. (K) Quantification of Ki67⁺ cells in control ducts (black bar, n = 5), control end buds (gray bar, n = 4), and Par3-depleted (white bar, n = 5) glands. Error bars, SD. (*) P = 0.0004, control duct versus control end bud; (**) P = 0.016, shPar3 versus control duct; (**) P = 0.20, shPar3 versus control end bud.