Figure 1

Seven-week post-lactation mouse mammary epithelium is fully regenerated and similar to age-matched virgin tissue. (a) Outline of experimental design. Mice were mated at 9 weeks of age, went through a normal pregnancy and nursed pups for 3 weeks. Involution occurred over an approximately 3-week period after pups were removed. After a further 4 weeks, when the animals were in total 22 weeks old, tissue was harvested. (b), (d) Carmine-stained whole mount of age-matched virgin (AMV) fourth mammary fat pad. (c), (e) Carmine-stained whole mount of parous fourth mammary fat pad. (b), (c) Bar = 3 mm. (d), (e) Bar = 750 μm. (f) H & E-stained section of AMV fourth mammary fat pad. Bar = 20 μm. (g) H & E-stained section of parous (7-week post-lactation) fourth mammary fat pad. Bar = 20 μm. (h) H & E-stained section of parous (3-week post-lactation) fourth mammary fat pad showing collapsed ducts (arrowheads). Bar = 20 μm.