Whole-mount morphology of mammary glands demonstrating the effect of hormonal treatments in intact and ovariectomized ACI rats after 39 weeks of treatment with various hormone combinations (X20). Shown are number 4 mammary glands of ACI rats at 45 weeks of age from the following groups: intact untreated (A), OVX untreated (B), intact treated with 10 μg of estrogen (low E) (C), OVX treated with low E (D), intact treated with (30→ 3 mg of E) (high E) (E), OVX treated with high E (F), intact treated with 30 mg of progesterone (P) (G), OVX treated with 30 mg of P (H) intact treated with low E plus 30 mg of P, (I), OVX treated with low E plus 30 mg of P (J), OVX treated with high E plus 30 mg of P (K), and OVX treated with high E plus 30 mg of P plus 30 mg of testosterone propionate (L).