Tamoxifen sex reverses alligator embryos at male producing temperature, but is an antiestrogen in female hatchlings

Tamoxifen is an anticancer drug widely used in the treatment of estrogen-dependent breast cancer. In hatchling alligators (Alligator mississippiensis ) it acts as a pure antiestrogen in that it completely blocks the effect of estradiol-induced oviductal hypertrophy and completely blocks the estradiol-induced hepatic vitellogenin secretion. Paradoxically, when injected into alligator eggs incubated at 33 degree C, a temperature which would normally result in 100% male hatchlings, tamoxifen "sex reverses" the embryos into apparently normal female hatchlings.