- The OECD program to validate the rat Hershberger bioassay to screen compounds for in vivo androgen and antiandrogen responses. Phase 1: use of a potent agonist and a potent antagonist to test the standardized protocol. Owens, W., Zeiger, E., Walker, M., Ashby, J., Onyon, L., Gray, L.E. Environ. Health Perspect. (2006)