title: Cranial neural crest cell migration in cockatiel Nymphicus hollandicus (Aves: Psittaciformes).
abstract: Parrots have developed unique jaw muscles in their evolutionary history. The M. pseudomasseter, which completely covers the lateral side of the jugal bar, is regarded as a jaw muscle unique to parrots. In a previous study, I presented a hypothesis on the relevance of modifications in the regulation of cranial neural crest cell (NCC) development to the generation of this novel jaw muscle based on histological analyses (Tokita [2004] J Morphol 259:69-81). In the present study, I investigated distribution and migration patterns of cranial neural crest cells (NCCs) through parrot embryogenesis with immunohistochemical techniques to further understand the role of cranial NCCs in the evolution of the M. pseudomasseter, and to provide new information on the relative plasticity in cranial NCC migration at early stages of avian development. The basic nature of cranial NCC development was mostly conserved between chick and parrot. In both, cranial NCCs migrated from the dorsal tip of the neural tube in a ventral direction. Three major populations were identified in their cranial NCCs. Migration pathways of these cells were almost identical between chick and parrot. The principal difference was seen in the relative timing of cranial NCC migration. In the parrot, cranial NCC migration into the first pharyngeal arch was more advanced than in the chick at early stages of development. Such a temporal shift in cranial NCC migration might influence architectural patterning of parrot jaw muscles that generates new muscle like M. pseudomasseter.
authors.affiliation: Department of Zoology, Graduate School of Science, Kyoto University, Sakyo, Kyoto 606-8502, Japan. tokky@zoo.zool.kyoto-u.ac.jp
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Tokita
mesh_terms: D000818:Animals; D018959:CD57 Antigens / Q000378:metabolism; D002465:Cell Movement; D046410:Cockatoos / Q000502:physiology*; D007568:Jaw / Q000033:anatomy & histology; D009132:Muscles / Q000033:anatomy & histology; D009432:Neural Crest / Q000166:cytology / Q000502:physiology*; D010311:Parrots / Q000196:embryology / Q000502:physiology*; D012886:Skull / Q000502:physiology*
chemical_list: D018959:CD57 Antigens