Fig. 2. Expression of WNT pathway genes at early stages of mammary development. (A,B) In-situ hybridization of a ³⁵S-labeled probe for Wnt3 to a parasagittal paraffin section of an E10.5 embryo photographed in bright field (A) and dark field (B) with red stage illumination. The signal appears as red grains and is indicated by arrows. (C-L) Whole-mount in-situ hybridization using the probes indicated. The signal appears red-brown and mammary region expression is indicated by arrows in each panel. Insets in panels C,E,F,G represent higher magnification photographs of the regions indicated by arrows in each panel.