Effect of a new anti-oestrogen and anti-implantation agent, CDRI-85/287, on tubal transport, development and viability of rat embryos.

The effect of CDRI-85/287, a pure nonsteroidal anti-oestrogen, on the rate of tubal transport and development and viability of embryos in rats was investigated. Single postcoital oral administration of an anti-implantation dose (2.5 mg kg-1) resulted in a mild acceleration in the passage of embryos through the oviduct; however, their rates of recovery, cleavage, blastocyst formation and zona shedding remained unaffected. Morphologically normal embryos were recovered from the genital tract up to Day 12 post coitum. Embryos recovered from CDRI-85/287-treated rats on Days 4 and 8 post coitum developed to normal term fetuses when transferred to uteri of untreated females. The compound therefore did not seem to have any deleterious direct effect on development or viability of rat embryos.