Expression pattern of the epithelial V-like antigen (Eva) transcript suggests a possible role in placental morphogenesis

Adhesive mechanisms are considered to be of crucial importance for blastocy st adherence to the uterine wall, as well as for the interactions between e mbryonal and decidual tissues during hemochorial placenta formation. Epithe lial V-like Antigen (Eva) is a novel hemophilic adhesion molecule of the im munoglobulin superfamily, which during mouse embryonic development is expre ssed by various differentiating epithelia. In the present paper we describe Eva expression during mouse trophoblast invasion and placental morphogenes is, analysing day 5.5 to 18.5 postcoitum (p.c.) placentas and deciduomas by in situ hybridization. Eva transcripts were detected in spongiotrophoblast cells from 7.5 to 18.5 days p.c. Expression was uniform at early stages, but after day 11.5, p.c. became limited to the invasive subpopulation of spongiotrophoblasts (known as glycogen cells). Trophoblast giant cells did not express Eva in any of t he stages analysed. Besides trophoblasts, also early postimplantation decid ua was positive for Eva transcripts. In decidual tissue, Eva expression was present at day 5.5 p.c., peaked at day 7.5 p.c., and declined on successiv e days. The expression pattern of Eva transcripts suggests that during mous e placenta formation, its protein product may play a role in the processes of trophoblast invasion, decidual re sponse, and trophoblast-decidual inter action. Dev. Genet. 23:317-323, 1998. (C) 1998 Wiley-Liss, Inc.