Total suppression of pregnancy in mice by post-coital administration of neuraminidase.

Because of certain analogies between the spread of tumors and different steps of pregnancy culminating in egg implantation and invasive growth, pregnant mice were treated at different intervals post coitum with two thrombocytopenic agents which can reduce metastases by interfering with vascular lodgement and growth of tumor cells. It was found that both neuraminidase and antiplatelet serum were active against pregnancy, the enzyme being by far the more effective of the two. The mechanism of this effect involves both egg implantation and egg development. The effect cannot be explained solely by the thrombocytopenia produced by both agents.