Ectomesenchyme has properties similar to mesenchyme. The origin of the ectomesenchyme is disputed. It is either like the mesenchyme, arising from mesodermic cells, or conversely arising from neural crest cells The neural crest is a critical group of cells that form in the cranial region during early vertebrate development. 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, notably, 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.