Figure 4.
Rescue of the PR−/− phenotype in PR−/− and PR+/+ chimeric epithelia. (Left) Whole-mount preparation of cleared PR+/+.RAG1−/− fat pad implanted with a mixture of PR−/− (red) epithelium and ROSA26.PR+/+ epithelium (blue) in a 1:1 ratio. The engrafted mammary gland was removed after the recipient had given birth, subjected to X-Gal staining, and whole-mounted.(Bar in Upper corresponds to 2 mm; bar in Lower, to 200 μm). (Center) Whole-mount preparation of cleared PR+/+.RAG1−/− fat pad injected with a mixture of PR−/−.ROSA26 (blue) epithelium and PR+/+ epithelium (red) injected in a 1:10 ratio, treated as for Left. (Bar corresponds to 200 μm.) (Right) Adjacent histological sections of an area with PR−/−.ROSA26 alveolar structures. (Upper) Expression of β-casein in wt and PR−/−.ROSA26 alveoli. (Lower) Control without primary antibody. Arrow indicates PR−/−.ROSA26 alveolus expressing β-casein. (Bar corresponds to 50 μm.)