Fig. 7. Model for neural crest lineage segregation. Neural crest (NC) progenitors identified by in vitro clonal analysis are ordered according to their number of developmental potentials [data taken from elsewhere (Baroffio et al., 1991; Trentin et al., 2004)]. In the cephalic NC, neurons (N), glia (G), melanocytes (M) and mesectodermal derivatives – myofibroblasts (F) and cartilage (C) – arise from diverse `intermediate' pluripotent and bipotent progenitors, which suggest that committed cells are generated through progressive restrictions in the potentialities of a putative `totipotent-like' NC stem cell (broken circle). In the trunk NC, clonogenic cells endowed with chondrogenic potential (blue) are not recovered; however, various myofibroblastic (non-chondrogenic) progenitors (pink) are present as in the cephalic NC. Self-renewal was demonstrated for rat trunk GNF-like cells (Stemple and Anderson, 1992), and for quail trunk and cephalic GM and GF progenitors (Trentin et al., 2004).