part of part of surrounds surrounds blastocele extraembryonic structure trophectoderm mural trophectoderm (...) the trophoblast develops rapidly so that contact may be made with the maternal uterine tissues when conditions are appropriate. We have here an excellent example of an embryonic adaptation, the development of a structure never present in either adult or embryo of 'lower' vertebrates.[well established][VHOG] EHDAA2:0001206 UBERON:0006265 mural trophoblast The part of the trophectoderm which surrounds the blastocoelic cavity. [See_Kaufman_MH_and_Bard_JBL, The_anatomical_basis_of_mouse_development_(1999)_San_Diego:_Academic_Press, p.10][VHOG] EMAPA:16047 Trophectoderm that surrounds blastocyst cavity. VHOG:0000597 EHDAA:58 entire extraembryonic component transitional anatomical structure