The Somite-Muscle Relationship in the Avian Embryo

Abstract

The trunk, limb, and tongue muscles originate from the somites (Christ et al. 1974, 1986; Chevallier et al. 1976). The muscle-forming cells (MF cells) are determined at very early stages of development (Krenn et al. 1988). The ways of MF cell separation from the dermomyotome are different with regard to the muscle groups examined. The intrinsic muscles of the back arise from the myotomes (Christ et al. 1986) which represent epithelially arranged derivatives of the somites. The abdominal muscles develop from the ventrally situated epithelial somite buds consisting of both dermatome and myotome cells (Christ et al. 1983). The limb and tongue muscles differentiate from MF cells that have migrated from the dermomyotomes (resp. dermatomes) to their destination as still replicating fibroblast-like cells. The modalities of MF cell separation seem to depend on the presence of different dermomyotome compartments which possibly arise by interactions between the somites and the environment (Jacob et al. 1974).