Timeline for 5-bromo-2-deoxyuridine (BrdU) injections and hormone treatments for each experiment. (A) Sex differences and the effects of oestradiol on cell proliferation were tested by postnatal day (PN) 0 hormone treatment with euthanasia 6 h after injection of BrdU. (B) Sex differences and the effects of oestradiol on short-term cell survival were tested by PN0 hormone treatment followed by euthanasia at PN4. (C) Sex differences and the effects of oestradiol on long-term survival and cell fate were tested by PN0 and PN1 hormone and BrdU treatments followed by euthanasia at PN21 and IHC processing for BrdU+cells. (D) Sex differences and the effects of antagonizing endogenous oestradiol were tested by treatment on PN0 and PN1 with formestane, tamoxifen or vehicle and BrdU followed by euthanasia at PN2 and IHC processing for BrdU+ cells.