Ectodermal markers delineate the neural fold interface during avian neurulation

The formation and morphogenesis of the neural folds are important processes underlying neurulation. We showed previously that these processes comprise four key events in avian embryos: epithelial ridging, kinking, delaminatio n, and apposition. Collectively, these events establish the paired, bilamin ar neural folds, which fuse in the dorsal midline during late neurulation t o close the neural groove and to establish the neural tube. Here, we use an antisense riboprobe for a new gene called Plato, as well as an antibody fo r a previously cloned transcription factor, AP-2, as markers to identify cr itical subpopulations of ectodermal cells during the formation and morphoge nesis of the avian neural folds. Plate antisense riboprobe marks the crania l neural ectoderm and premigratory cranial neural crest cells, whereas AP-2 antibody marks the epidermal ectoderm and the early migratory neural crest . We show that subpopulations of ectodermal cells at the forebrain and midb rain levels undergo considerable rearrangement within the neural fold trans ition zone, which redistributes incipient neural crest cells from the neura l ectodermal side of the forming neural fold interface to the epidermal ect odermal side. Additionally, we show that nato and AP-2 provide useful marke rs for delineating the incipient neural fold interface. Anat Rec 260:106-10 9, 2000. (C) 2000 Wiley-Liss, Inc.