Rat strain-specific effects of 17β-estradiol on mammary gland morphology and histology. A, Representative whole mount of abdominal/inguinal mammary glands from a 10 weeks old ACI female. Left, anterior. Right, posterior. Up, medial. Down, lateral. The rectangle illustrates the approximate region of the abdominal gland illustrated in Panels B. Scale bar, 5mm. B, Representative images of mammary gland whole mounts from ACI and BN rats, either sham treated (Ctrl) or treated with E2 for 1, 3 or 12 weeks (n = 3). Scale bars, 2mm. C, Representative images of mammary tissues, sectioned and stained with hematoxylin and eosin, from ACI and BN rats treated as described in Panels B (n ≥ 5). Scale bars, 100 μm.