part of extravillous trophoblast extravillous trophoblast cell 2018-09-25T11:15:32Z BTO:0006208 BrendaTissueOBO EVT cell Marion The outermost layer of trophoblast, produced by cytotrophoblast where there is direct contact with maternal decidua rather than blood. The EVT cells travel into the decidua, reacting with NK cells and invading maternal blood vessels feeding the placenta, softening the walls and replacing the lining with fetal tissue, a process called conversion. intermediate trophoblast cell interstitial trophoblast cell