tissue neurectoderm ectoderm-derived structure non-neural ectoderm Gene notes: One of the first genes to be expressed in nonneural ectoderm in amphioxus is BMP2/4 (Panopoulou et al. 1998). BMP2/4 homologues appear to have a very ancient role in distinguishing neural from nonneural ectoderm; in Drosophila as well as in amphioxus and vertebrates, BMP2/4 homologues are expressed in nonneural ectoderm and function in distinguishing neural from nonneural ectoderm (Francois & Bier, 1995 ; Sasai et al. 1995 ; Wilson & Hemmati-Brivanlou, 1995; Panopoulou et al. 1998). A change in level of BMP2/4 from very high in nonneural ectoderm to low in neural ectoderm appears to be a key factor in development of neural crest (Baker & Bronner-Fraser,1997a,1997b;Erickson&Reedy,1998;Marchantet al.1998 ;Selleck et al. 1998). After gastrulation, neural crest cells are specified at the border of the neural plate and the non-neural ectoderm. todo - epidermis? todo - track down EHDAA2 class in new release