Morphological observations made on forty-nine uteri from twenty-three control and twenty-six IUD rhesus monkeys killed between Days 15 and 20 of their natural menstrual cycle, were related to the physiological condition of the corresponding ovary.
The only differences between control and IUD specimens of similar luteal age were the presence of (a) a markedly flattened surface epithelium in areas of contact with the IUD; (b) erosion of the surface epithelium and underlying stroma, with fibrosis and extensive leucocytic infiltration, in the lateral angles of the uterine lumen; (c) polymorphonuclear leucocytes lying immediately beneath the surface epithelium, together with variable leucocytic infiltration into the epithelium and the underlying stroma. These changes were not related to the physiological state of the ovary, previous surgery of the uterus, or to the length of time the IUD was retained in the uterine lumen.
A deciduomal reaction could be induced both in ovariectomized, hormonally-stimulated and in naturally cyclic monkeys as a response to endometrial trauma. In both groups, there was no difference in the appearance and proliferation of the deciduomal reaction in control and IUD monkeys.