C57BL/6J mice were ovariectomized at 8 weeks of age. At the time of surgery, mice were randomized to receive (subcutaneous implantation) a Silastic capsule (i.d. 1.02 mm; o.d. 2.16 mm) containing 5 mm of dry-packed 17β-E2 (n=5 per group per timepoint). Controls received an empty capsule. Analysis of serum demonstrated consistent levels of E2 in the blood and at 1, 2 and 4 weeks, which was predictive of an increase in uterus weight over those time points (Supplementary Figure 1).
