Figure 7. Direct contact between embryo and uterine stroma is involved in embryonic cell survival and invasion.

(A) Apoptosis of luminal epithelium was not apparently observed on day 5 evening, when the disappearance of luminal epithelium attached to the embryo occurred in the control mice. In contrast, apoptosis was observed in the trophoblast attached to intact luminal epithelium in Hif2a-uKO mice. Scale bar, 200 μm, arrowhead, an embryo. (B) Transmission electron microscopic analyses of embryo-uterine interface at 1900 hours on day 5 demonstrated the newly-formed gaps between the stroma and the luminal epithelium (arrowhead) and the invading trophoblast into these gaps in the control mice, but not in Hif2a-uKO mice. Scale bar, 1 μm; s, stroma; tro, trophoblast; le, luminal epithelium. (C and D) Expression of MT2-MMP and LOX at the stroma of implantation sites collected by laser capture microdissection was downregulated in Hif2a-uKO mice compared with the controls *P < 0.05, n = 4, mean ± SEM, Student’s t test.