Fig. 4. Absence of Wnt5a accelerates mammary development in mice. (A) Carmine-stained whole-mount #1 gland from E18.5 wild-type and Wnt5a^-/- mice. (B) Carmine-stained mammary tissue that was grafted under the kidney capsule of 3-week-old ICR/SCID mice demonstrates accelerated development in Wnt5a^-/- tissue compared with wild-type tissue after 1 week. Increased ductal invasion, extensive branching and larger terminal end buds were noted in the Wnt5a^-/- tissue (arrowheads). (C) Brdu analysis of mammary tissue transplanted under the kidney capsule demonstrates a twofold increase in proliferation of Wnt5a^-/- mammary tissue compared with wild type (P=0.0005). (D,E) Whole-mount staining of mammary tissue inserted into cleared fat pads of 3-week-old ICR/SCID hosts shows accelerated mammary development of Wnt5a^-/- epithelium (E) compared with wild-type epithelium (D) after 2 weeks of development. Arrowheads indicate terminal end buds (TEBs).