Significance of the cranial neural crest

Abstract

The cranial neural crest has long been viewed as being of particular significance. First, it has been held that the cranial neural crest has a morphogenetic role, acting to coordinate the development of the pharyngeal arches. By contrast, the trunk crest seems to play a more subservient role in terms of embryonic patterning. Second, the cranial crest not only generates neurons, glia, and melanocytes, but additionally forms skeletal derivatives (bones, cartilage, and teeth, as well as smooth muscle and connective tissue), and this potential was thought to be a unique feature of the cranial crest. Recently, however, several studies have suggested that the cranial neural crest may not be so influential in terms of patterning, nor so exceptional in the derivatives that it makes. It is now becoming clear that the morphogenesis of the pharyngeal arches is largely driven by the pharyngeal endoderm. Furthermore, it is now apparent that trunk neural crest cells have skeletal potential. However, it has now been demonstrated that a key role for the cranial neural crest streams is to organise the innervation of the hindbrain by the cranial sensory ganglia. Thus, in the past few years, our views of the significance of the cranial neural crest for head development have been altered.

Controlled levels of canonical Wnt signaling are required for neural crest migration

“…They are induced along the entire length of neuraxis as a bilateral, segmented stripe of cells at the lateral border of the neural plate and nonneural ectoderm (Hall, 2008;Le Douarin and Kalcheim, 1999;Sauka-Spengler and Bronner-Fraser, 2008;Steventon et al, 2005). NC cells are subdivided into cranial (Graham et al, 2004;Cordero et al, 2011), cardiac (Kirby et al, 1983;Keyte and Hutson, 2012), vagal (Kuo and Erickson, 2011;Peters-Van Der Sanden et al, 1993;Burns and Le Douarin, 1998;Yntema and Hammond, 1954), trunk (Bronner-Fraser and Fraser, 1989;Serbedzija et al, 1994) and sacral (Burns and Le Douarin, 1998;Anderson et al, 2006) NC cells due to their diversity along neuraxis ( Fig.1.1A). Upon closure of the neural plate, NC cells undergo epithelial-to-mesenchymal transition (EMT) (Ahlstrom and Erickson, 2009;Alfandari et al, 2010;Berndt et al, 2008 andDuband, 2010) allowing them to delaminate from prospective neural tube and migrate throughout the embryo ( Fig.1.1B).…”

Spatial relations between avian craniofacial neural crest and paraxial mesoderm cells

“…These interactions are bidirectional, with signals from crest cells regulating the rate of muscle differentiation (Tzahor et al, 2004) and patterns of muscle morphogenesis (Noden, 1986;Olsson et al, 2001;Borue and Noden, 2004), and mesoderm participating in the positional specification of nearby crest populations (Trainor and Krumlauf, 2001;Trainor et al, 2002 ). Both components also receive organizing influences from surface ectoderm and underlying pharyngeal endoderm (Couly et al, 2002;Rubin et al, 2003;Graham et al, 2004).…”

“…In contrast, neural crest cells that populate each of the branchial arches do carry positional biases (Hörstadius and Sellman, 1946;Noden, 1983a;Cerny et al, 2004a), which in large part define their responses to signals from neighboring tissues (Trainor and Krumlauf, 2000;Graham et al, 2004). In this context, slight shifts in the location of the crest-mesoderm interface are likely to have profound primary effects on craniofacial skeletogenesis (Schneider, 1999;Helms and Schneider, 2003;Kuratani, 2005) and secondary consequences for the organization of muscles and other soft tissues.…”

21st Century neontology and the comparative development of the vertebrate skull

“…In this regard, a gradually building consensus concerning the cumulative experimental evidence in vertebrates suggests that the development of BA1 hard tissues involves a combination of both prepattern and epigenetic mechanisms and the elaboration of developmental programs is consensual at heart. Clearly, CNC cells are bringing with them both factors crucial for their interpretation of their environment and the malleability (plasticity) to interpret the distinct, specific focal inductive influences in their environment; apparently, so too can the epithelia be characterized (e.g., Couly et al, 2002;Depew et al, 2002a,b;Trainor et al, 2002;Santagati and Rijli, 2003;Schneider and Helms, 2003;Graham et al, 2004;Tucker and Lumsden, 2004).…”