has potential to develop into has potential to develop into Teleostei simple columnar epithelium endoderm mesoderm primitive streak http://upload.wikimedia.org/wikipedia/commons/f/f4/Gray13.png UBERON:0004341 EHDAA2:0001525 NCIT:C28402 EMAPA:16072 primitive streak - blastopore - germ ring EHDAA:185 (...) the blastopore equivalent of chordates (germ ring in fish, marginal zone/blastopore lip in frog and node/primitive streak in chick and mouse) (...) (reference 1); Indeed, the primitive streak has been considered the homologue of the blastopore since the 1870s (reference 2).[well established][VHOG] Wikipedia:Primitive_streak MESH:D054240 SCTID:361438007 FMA:293110 The primitive streak is a structure that forms during the early stages of avian, reptilian and mammalian embryonic development[WP]. the midline ridge of the embryonic epiblast that later develops into mesoderm and endoderm[MP]. VHOG includes a very broad grouping here based on http://www.ncbi.nlm.nih.gov/pubmed/9609826 UMLS:C0033153 VHOG:0001202 embryonic tissue