Immunohistochemical localization of integrin αVβ3 in cryosections of ovine endometrial tissue during the estrous cycle (A, day 13 cyclic, B, day 17 cyclic) and at day 13 of pregnancy (C-F, day 13 pregnant). Positive reactivity (brown) was strongest in the glands (G) and blood vessels, while very weak or no reactivity was detected in the superficial glands (SG) or luminal epithelium (LE). Panels A, C and D illustrate the differences in subepithelial stroma (SES) reactivity to anti-integrin αVβ3 in caruncular (CAR) and intercaruncular (ICAR) regions at different magnifications. Intercaruncular SES reactivity varied among the sheep, ranging from moderate (D) to relatively weak and diffuse as seen in panel E. Control sections (F) were treated with mouse IgG substituted for primary antibody. Stroma (S). Bar = 50 μm.