Fig. 3. Involution is delayed in C/EBP null mammary glands. Comparison of mammary gland histology during involution in wild-type (WT) and C/EBP null (KO) mice. (A) Representative photographs of sections from two mice per indicated time points (original magnification 50x). (B) Quantification of the areas occupied by adipocytes in mammary gland sections at days 1-4 of involution (three to four mice per time point). **P<0.01, ***P<0.01, *****P<0.00001, by two-way ANOVA with follow-up tests.