Ectomesenchyme has similar properties to mesenchyme. The origin of the ectomesenchyme is disputed whether it is like the mesenchyme, arose from mesodermic cells, or differently arose from neural crest cells which are a critical group of cells that form in the cranial region during early vertebrate development. Thus, ectomesenchyme plays a critical role in the formation of the hard and soft tissues of the head and neck such as bones, muscles, teeth, and, most important, the branchial arches.
^Weston JA, Yoshida H, Robinson V, Nishikawa S, Fraser ST, Nishikawa S (2004). "Neural crest and the origin of ectomesenchyme: neural fold heterogeneity suggests an alternative hypothesis". Dev. Dyn.229 (1): 118–30. doi:10.1002/dvdy.10478. PMID14699583.