Abstract
The present investigation studied the influence of different types of intra-uterine devices (IUDs) especially that of a copper IUD, on the incorporation of 3H-thymidine and 5-3H-uridine into the endometrium of the rabbit. “Inert” polyethylene IUDs had no effect on the incorporation of these labelled precursors. The effect of the copper IUD was always compared with that of an “inert” IUD. In non-stimulated rabbits, the incorporation of 3H-thymidine was increased in the copper influenced horn. The incorporation of 3H-thymidine in control and Cu-IUD-containing horns reached a maximum at 48 hours after HCG stimulation, but was significantly lower in the copper-containing horn than in the control horn. On the fifth day of pseudopregnancy, the incorporation of 3H-thymidine was significantly higher in the copper IUD-containing horn. The total amount of DNA in the endometrium increased during early pseudopregnancy, but this increase was markedly reduced in the presence of copper. The copper IUD had no influence on the rate of incorporation of 5-3H-uridine in non-stimulated rabbits, whereas it caused a higher incorporation on the fifth day of pseudopregnancy.