part of part of trophoblast extravillous trophoblast UBERON:0000426 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. FMA:86561 BTO:0002366 intermediate trophoblast interstitial trophoblast embryonic structure