Neural crest and the patterning of vertebrate craniofacial muscles

Abstract

Patterning of craniofacial muscles overtly begins with the activation of lineage-specific markers at precise, evolutionarily conserved locations within prechordal, lateral, and both unsegmented and somitic paraxial mesoderm populations. Although these initial programming events occur without influence of neural crest cells, the subsequent movements and differentiation stages of most head muscles are neural crest-dependent. Incorporating both descriptive and experimental studies, this review examines each stage of myogenesis up through the formation of attachments to their skeletal partners. We present the similarities among developing muscle groups, including comparisons with trunk myogenesis, but emphasize the morphogenetic processes that are unique to each group and sometimes subsets of muscles within a group. These groups include branchial (pharyngeal) arches, which encompass both those with clear homologues in all vertebrate classes and those unique to one, for example, mammalian facial muscles, and also extraocular, laryngeal, tongue, and neck muscles. The presence of several distinct processes underlying neural crest:myoblast/myocyte interactions and behaviors is not surprising, given the wide range of both quantitative and qualitative variations in craniofacial muscle organization achieved during vertebrate evolution.

Connecting muscle development, birth defects, and evolution: An essential role for muscle connective tissue

“…Most of the head muscles derive from the cranial mesoderm, mesoderm lying on either side of the neural tube and extending rostrally from the prosencephalon and caudally toward the somites. Unlike the paraxial mesoderm that segments into somites in the trunk, the cranial mesoderm is unsegmented, but does contain different regions that give rise to different cranial muscles (reviewed in Michailovici et al, 2015; Ziermann et al, 2018). The most rostral region (also termed the prechordal mesoderm) gives rise to the extraocular muscles.…”

“…Interestingly, the pharyngeal cranial mesoderm region does not give rise exclusively to head muscles, but has also been found to give rise to major components of the heart (Lescroart et al, 2015; Lescroart et al, 2010). The tongue muscles derive from anterior somites, from which muscle progenitors migrate to the tongue region (reviewed in Diogo et al, 2015; Ziermann et al, 2018). The MCT comes from a third embryonic tissue, the neural crest.…”

“…During this time, muscle progenitors begin the process of myogenesis and are specified into myoblasts. Unlike axial or limb muscles, Pax3 and Pax7 are not the initial key regulators of myogenesis, but instead distinct regulatory networks of multiple transcription factors including Pitx2, Tbx1, Islet1, Lhx2, Nkx2.5, MyoR and Capsulin are required, but then converge on the requirement of MyoD and Myf5 for myoblast specification and Myogenin for myocyte differentiation (reviewed by Diogo et al, 2015; Harel et al, 2012; Michailovici et al, 2015; Tzahor, 2009; Ziermann et al, 2018). The initial steps of myogenesis leading up to the specification of MyoD+ myoblasts are independent of signals from the neural crest (Tzahor et al, 2003).…”

“…The neural crest plays a key role in regulating the morphogenesis and pattern of cranial muscles (reviewed by Noden and Francis-West, 2006; Noden and Trainor, 2005; Ziermann et al, 2018). Initial evidence for the important role of the neural crest came from embryological transplantation experiments.…”

Bone Surface Micro‐Topography at Craniofacial Entheses: Insights on Osteogenic Adaptation at Muscle Insertions

“…These primates are known to have similar mandibular musculature to other primates (Diogo et al, ; Diogo and Wood, ). These muscle groupings having their origins in specific neural crest populations forming their facial patterns (Ziermann et al, ).…”