Abstract
Summary
The normal growth of the mammary glands of immature female rats of the Sprague-Dawley-Rolfsmeyer strain was compared to that induced by 1 μg/day of estradiol benzoate (EB) from 40 to 80 days of age by the DNA method. The mean DNA/100g BW of normal female rats at 40 days of age was 2.60 ± 0.16 mg, at 60 days 3.42 ± 0.12 mg, and at 80 days 3.62 ± 0.18 mg. The rats injected with EB for 20 days (age 40 days) showed mean DNA/100 g of 2.81 ± 0.14 mg, significantly higher (P <0.001) than the control, with no difference in BW. After 40 days of EB (age 60 days), the mean DNA/100 g BW was 3.45 ± 0.15, the same as the control, but had a lower mean body weight of 15 g. After 60 days of EB (age 80 days), the mean DNA/100 g BW was 3.0 ± 0.18 mg, significantly different from the control (0.02 > P <0.01), but had a lower mean body weight of 39 g. The treated rats plateaued in their body weight after 40 days of treatment, whereas the controls showed continuous growth.
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