part of part of develops_from trophoblast CALOHA:TS-1070 trophoderm The postimplantation derivatives of the trophectoderm, which make up most of the fetal part of the placenta uberon UBERON:0000088 massa cellularis externa UMLS:C0041178 FMA:83029 Aggregate of cells forming the outer layer of a blastocyst, which provide nutrients to the embryo and develop into a large part of the placenta. They are formed during the first stage of pregnancy and are the first cells to differentiate from the fertilized egg. [Wikipedia:Trophoblast] BTO:0001079 EV:0100120 the mesectodermal cell layer arising from the trophectoderm that erodes the uterine mucosa and contributes to the formation of the placenta[MP] trophoblastic trophoblast layer trophoblastus MESH:A11.936 GAID:1152 the mesectodermal cell layer arising from the trophectoderm that erodes the uterine mucosa and contributes to the formation of the placenta blastocyst embryonic structure trophectoderm