The present investigation studied the influence of different types of intra-uterine devices (IUDs) especially that of a copper IUD, on the incorporation of 3-H-thymidine and 5-3-H-uridine into the endometrium of the rabbit. "Inert" IUD. In non-stimulated rabbits, the incorporation of 3-H-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 3-H-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 5-3-H-uridine in non-stimulated rabbits, whereas it caused a higher incorporation on the fifth day of pseudopregnancy.
PIP: The influence of polyethylene and copper intrauterine devices (IUD) on the incorporation of triated-thymidine and 5-tritiated-uridine into the endometrium of rabbits was studied after stimulation with human chorionic gonadotropin (HCG). The polyethylene devices had no effect on the uptake of labeled materials. The incorporation of tritiated-thymidine was increased in nonstimulated animals with a copper IUD in place. After HCG stimulation, the uptake of tritiated-thymidine reached a maximum 48 hours after stimulation, and was significantly greater in control horns (platinum IUD) than in copper IUD horns (p less than .02). However, the incorporation of tritiated-thymidine was significantly higher in copper IUD horns than in control horns 120 hours after stimulation (p less than .001). The amount of increased DNA in the endometrium during pseudopregnancy was considerably reduced in the presence of a copper IUD. The incorporation of 5-tritiated-uridine was not affected by the copper IUD in nonstimulated animals, whereas a significant amount was incorporated at 120 days in HCG-stimulated animals (p less than .001). Results indicate that the copper IUD can alter the nucleic acid metabolism of the endometrium in the rabbit.