Fig. 1.

In utero and lactational exposure to BB reduces ductal branching and TEB numbers in offspring. (A) Dietary regimen. Wild-type (WT) dams were mated with Wnt1-Tg males. Dams were fed control (CAS) diet or the BB-supplemented CAS diet from mating through pregnancy and lactation. Wnt1-Tg and WT female pups were weaned to CAS diet. Inguinal mammary gland (4) was collected for RNA (right MG) and whole mount (left MG) from weaning (PND21) pups. For the tumor study, Wnt1-Tg female offspring that were exposed via maternal diet to either CAS (n = 33) or BB (n = 28) were monitored weekly by palpation for tumor development. Two weeks post-tumor detection, serum was collected and tumors were harvested for RNA and protein analyses. (B) Whole-mount analysis revealed excessive branching and hyperplasia in mammary glands of Wnt1-Tg female pups at weaning (PND21), compared with WT mice, as previously reported (19). (C) Shown are the mammary glands of PND50 virgin WT female mice exposed to CAS or BB via maternal diet. (D) Ductal branching was quantified in PND21 and PND50 WT mice. (E) Quantification of mammary TEB in PND21 and PND50 WT mice exposed to maternal CAS or BB diets. Results are mean ± SEM; *P < 0.05 relative to CAS (n = 5 mice per diet, per PND). Bar, 300 µm. 3× magnification.