Fig. 3. Mammary epithelial expression of MYC from D12.5-D15.5 of pregnancy promotes morphological changes consistent with precocious lactation. Hematoxylin and Eosin staining of number four mammary gland histological sections from MTB and MTB/TOM mice induced with doxycycline from D12.5-D15.5 of pregnancy and harvested at 1-day increments from D12.5 of pregnancy through day 1 postpartum (D1PP) (A-P). Uninduced MTB/TOM glands harvested at increasing intervals during lactation are also shown (Q-T). Results are representative of sections from three animals per group.