Myotomal myogenesis of axial muscle in the sturgeon Acipenser baeri (Chondrostei, Acipenseriformes)

Compared to teleost fishes, a unique character of the myogenesis of the plesiomorphic A. baeri is the fusion of myoblasts derived from the somite, leading to the formation of multinucleate muscle lamellae. Then, the lamellae are converted into cylindrical muscle fibres. The mechanism of transformation of lamellae into fibres is still debatable. Early embryonic muscle growth is mainly due to the hypertrophy of somite-cell derived stock. After hatching, hypertrophic growth occurs parallel to hyperplastic growth. Proliferatively active mesenchymal cells, which migrate from the intermyotomal space into the myotomes, participate in both processes.