Fig. 7. Expression of MYC from D12.5-D15.5 of pregnancy promotes apoptosis of mammary epithelial cells. Terminal deoxynucleotidyltansferase-mediated dUTP nick end-labeling (TUNEL) analysis was performed using the Apoptag Peroxidase Kit on mammary histological sections from MTB/TOM (A-D) and MTB control mice (E-H) induced with doxycycline from D12.5-D15.5 of pregnancy. TUNEL analysis was also performed on mammary gland histological sections from MTB/TOM (I-L) and MTB mice (M-P) during the post-induction period from day 16.5 of pregnancy to day 1 postpartum (D1PP). Images are representative of three animals per group.