Early embryonic development in the rat after maternal treatment with PGE2

Pregnant Sprague-Dawley rats were treated subcutaneously with PGE2 at doses of 50, 100, and 200 microgram on gestational days five through eight. Control animals received the solvent in a similar manner. On gestational day 9 the animals were killed by intracardiac perfusion with Karnovsky's fixative, uteri were removed, and a transverse central slice from each implantation site was embedded in araldite. The conceptus was located and 2-3 micron sections were made of each implantation site and examined at the light microscopic level. No significant structural changes were induced in any of the conceptuses, but an unusually wide range of embryonic stages was detected in both the control and the experimental groups of animals.