Outermost layer of cells in the blastodermic vesicle, which will develop into the trophoblast layer and then contact the endometrium and take part in establishing the embryo's means of nutrition.

distinction between trophectoderm and trophoblast unclear/inconsistent in many sources

The outer cellular layer of the mammalian blastocyst. [Evolution, Fourth_Edition_(2006)_McGraw-Hill, Function, Vertebrates:_Comparative_Anatomy, p.750, see_Kardong_KV][VHOG]

BTO has this has part of the trophoblast

uberon

trophectodermal

(...) 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]

UBERON:0004345

http://purl.obolibrary.org/obo/uberon.owl, http://purl.obolibrary.org/obo/cl.owl

• trophoblast