Visceral endoderm, a population of extraembyonic endoderm, is an extraembryonic tissue that functions in a regulatory capacity but does not contribute directly to the formation of any adult organs[PMID:15905405]. primitive endoderm-derived tissue which remains in contact with and surrounds the extra-embryonic ectoderm and the epiblast and provides signals for the differentiation and patterning of the epiblast; a small number of visceral endoderm cells also contribute to the endoderm of the embryonic gut[MP]. [ MP:0011186 http://www.ncbi.nlm.nih.gov/pubmed/15905405 ]