Figure 2.

EVT cells replace the uterine epithelium. Immunocytochemical double staining of invaded decidua (7 weeks gestational age) for cytokeratin 7 (Ck7, blue, serves as marker for glandular and uterine epithelium) and HLA-G (dark brown, serves as marker for EVT). No nuclear counterstain. (a) Overview shows the transitional zone between decidua capsularis (to the left) and decidua basalis (to the right) with uterine cavity above and intervillous space below. The decidua basalis includes prominent uterine glands (UG) with blue-labeled epithelia. (b) Inset shown in (a). Black arrows indicate the uterine epithelium. (c) Inset shown in (b). Higher magnification shows EVT cells (red arrows) breaking through the uterine epithelium at the opening of the UG, and an endoglandular EVT cell in the lumen of the gland.