title: Scanning electron microscopic evidence for physical segmental boundaries in the anterior presomitic mesoderm.
abstract: The metameric pattern of the axial skeleton is established during embryogenesis by somite formation from the unsegmented paraxial mesoderm (presomitic mesoderm). Here, we have investigated the morphology of the anterior presomitic mesoderm of chick embryos using scanning electron microscopy. We found periodically arranged transverse clefts in the anterior region of the presomitic mesoderm. These gaps can be regarded as physical boundaries between prospective somites in the determined zone of the presomitic mesoderm. This study provides additional evidence suggesting that prospective somite boundaries are not only marked by defined zones of gene expression, but are also accompanied by changes in cellular morphology that give rise to identifiable morphological segments.
authors.affiliation: Institute of Anatomy, University of Bonn, Nussallee 10, 53115 Bonn, Germany. Electronic address: qinpu@uni-bonn.de.
authors.forename: Qin
authors.initials: Q
authors.lastname: Pu
authors.forename: Ketan
authors.initials: K
authors.lastname: Patel
authors.forename: Jürgen
authors.initials: J
authors.lastname: Berger
authors.forename: Bodo
authors.initials: B
authors.lastname: Christ
authors.forename: Ruijin
authors.initials: R
authors.lastname: Huang
mesh_terms: D000818:Animals; D030161:Avian Proteins / Q000235:genetics / Q000378:metabolism; D051792:Basic Helix-Loop-Helix Proteins / Q000378:metabolism; D002642:Chick Embryo; D047108:Embryonic Development; D005109:Extracellular Matrix / Q000648:ultrastructure; D015870:Gene Expression; D018507:Gene Expression Regulation, Developmental; D016695:Glycosyltransferases / Q000235:genetics; D017403:In Situ Hybridization; D008648:Mesoderm / Q000378:metabolism / Q000648:ultrastructure*; D008855:Microscopy, Electron, Scanning; D019170:Somites
chemical_list: D030161:Avian Proteins; D051792:Basic Helix-Loop-Helix Proteins; D016695:Glycosyltransferases; C109424:hairy1 protein, Gallus gallus; C498394:LFNG protein, Gallus gallus
keywords: Chick embryo; Presomitic mesoderm; Segmentation; Somite; Somitogenesis