| Budget Amount *help |
¥4,030,000 (Direct Cost: ¥3,100,000、Indirect Cost: ¥930,000)
Fiscal Year 2011: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2010: ¥3,120,000 (Direct Cost: ¥2,400,000、Indirect Cost: ¥720,000)
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| Research Abstract |
Vertebrate body is mainly composed of head and trunk, which are combined with neck. To investigate the anatomical characteristics of neck, development of neck region, especially tongue muscles, was compared between various vertebrates. In agnathan, lamprey, anlage of hypobranchial muscle, homologous muscle to tongue muscles in gnathostome, developed behind and under pharyngeal arches. By comparing cephalic neural crest distribution and the anlage, undifferentiated muscle progenitor cells of the tongue muscles appear to develop in the cephalic neural crest just behind the arches. These phenomena were also observed in amniote embryos and confirmed by making chicken-quail chimera in which cephalic neural crest was transplanted. These results indicate that tongue muscles primordium originates from somites and migrates behind and under the arches as undifferentiated scattered cells and differentiates in the cephalic neural crest. In shark, however, the anlage was already differentiated to muscle cells and migrate behind the arches as several segmented streams of cells. This observation indicates that muscle development was secondarily changed in the lineage leading to shark in its evolution and development of fin muscle in shark also does not always shows ancestral state.
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