CDX2 and pelvic inflammatory disease: To determine if expression of the PID affected embryonic development in mice, PID mice were crossed with Tg(CDX2P-NLS-Cre) (hereafter referred to as CDX2) mice, which express Cre recombinase in intestinal tissues22, and the intestines and other internal organs were examined in bi-transgenic CDX2;PID animals.