Gpr177 is essential for mammary morphogenesis.

<p>Whole mount staining of the number four mammary glands reveals severe developmental defects associated with inactivation of Gpr177 by MMTV-Cre (Gpr177^MMTV) at virgin 1 month (v1M; A–C) and virgin 2 month (v2M; D–F). Asterisks and bracket indicate the residual epithelial components detected in the Gpr177^MMTV mutant. Arrows indicate the presence of TEB in the v1M control littermates. Enlargements of the insets (A–F) are shown in A′–F′. LN, lymph node. The average number of TEB (G) and branching (H), as well as the percentage of ductal occupancy (I), were examined in control (genotype: MMTV-Cre; Gpr177Fx/+, Gpr177Fx/Fx or Gpr177Fx/+) and Gpr177^MMTV for quantitative analysis (n = 3). Scale bars, 2 mm (A–F).