[Investigations on the contraceptive action of the Graefenberg ring. Historical review (author's transl)].

The biological activity of 2 Graefenberg rings was tested in vitro by electrone microscopy and X-ray microanalysis. The investigation showed that Graefenberg rings made of silver contain a varying amount of copper. The Graefenberg rings showed dissociation of copper in vitro which probably also occurred in the uterine cavity. The effect of the copper on the endometrium was probably a factor in the good contraceptive effectiveness of the Graefenberg silver ring compared for the silk thread intrauterine pessaries.