trophoblast

tro·pho·blast

noun \ˈtrō-fə-ˌblast\

Definition of TROPHOBLAST

: the outer layer of the mammalian blastocyst that supplies nutrition to the embryo, facilitates implantation by eroding away the tissues of the uterus with which it comes in contact allowing the blastocyst to sink into the cavity formed in the uterine wall, and differentiates into the extraembryonic membranes surrounding the embryo—called also trophoderm

—tro·pho·blas·tic \ˌtrō-fə-ˈblas-tik\ adjective