Molecular and cellular biology of avian somite development

Abstract

Much of our understanding of early vertebrate embryogenesis derives from experimental work done with the chick embryo. Studies of the avian somite have played a key role in elucidating the developmental history of this important structure, the source of most muscle and bone in the organism. Here we review the development of the avian somite including morphological and molecular data on the origin of paraxial mesoderm, maturation of the segmental plate, specification and formation of somite compartments, and somite cell differentiation into cartilage and skeletal muscle. © 2000 Wiley‐Liss, Inc.

Zac1 is expressed in progenitor/stem cells of the neuroectoderm and mesoderm during embryogenesis: Differential phenotype of the Zac1‐expressing cells during development

“…The ventral part of the somite (sclerotome) gives rise to the cartilage and bone of the vertebral column and ribs, whereas the dorsal part of somite (dermomyotome) produces the dermis of the back and the skeletal muscle of the body and limbs and the muscular connective tissue, except in the head muscles, which proceed from prechordal and paraxial mesoderm (Buckingham et al, 2003). The wide expression of the Zac1 gene in most of these tissues, as well as in most, if not in all, cellular phases, suggests that Zac1 could be a regulating control factor, like other transcription factors (Pax, bHLH, Sox, and so on) in chondrogenesis and myogenesis during embryonic development (Stockdale et al, 2000;Olsen et al, 2000;Moran et al, 2002;Yang and Karsenty, 2002).…”

Muscle stem cells and model systems for their investigation

“…The dorsal part of the somite retains its epithelial structure and becomes the dermomyotome, which itself is further regionalized. Dorsally, the dermomyotome generates the dermal layer of the forming skin of the back, while the cells from the medial region give rise to the deep muscles of the back, and those of the lateral region differentiate into body wall and limb skeletal musculature (Christ and Ordahl, 1995;Stockdale et al, 2000). As elegantly demonstrated in chick and mouse embryos (Gros et al, 2005;Relaix et al, 2005), the dermomyotome is also the source of satellite cells, which are known progenitors of adult skeletal muscles.…”

Formation of Vertebral Precursors: Past Models and Future Predictions

“…Soon after the PSM forms, the process of somitogenesis begins; cells in the PSM undergo changes in their adhesive and migratory properties and condense together to form epithelial blocks of cells known as somites. The somites bud off from the PSM at regular intervals, the first forming at the anteriormost end and with subsequent somites forming in a strict AP sequence (Gossler and Hrabě de Angelis, 1998;Stickney and Devoto, 2000;Stockdale et al, 2000). This budding of somites from the PSM compensates for the addition of cells via cell division and from the node, and keeps the PSM approximately constant in length, so that a wave appears to move down the AP axis leaving somites in its wake.…”