Outgrowth of normal chick limb bud mesoderm is dependent on the presence of a specialized epithelium called the apical ectodermal ridge. This ectodermal ridge is induced by the mesoderm at about the time of limb bud formation. The limbless mutation in the chick affects apical ectodermal ridge formation in the limb buds of homozygotes. The initial formation of the limb bud appears to be unaffect...

BACKGROUND The outgrowth of the vertebrate limb bud is the result of a reciprocal interaction between the mesenchyme and a specialized region of the ectoderm, the apical ectodermal ridge (AER), which overlies it. Signals emanating from the AER act to maintain the underlying mesenchyme, called the progress zone, in a highly proliferative and undifferentiated state. Removal of the AER results in ...

In vertebrates all skeletal muscles of trunk and limbs are derived from condensations of the paraxial mesoderm, the somites. Limb muscle precursor cells migrate during embryogenesis from somites to limb buds where migration stops and differentiation occurs. We have characterized lbx1 homeobox genes in chicken and mice and found them to be expressed in migrating limb muscle precursor cells in bo...

A central question in developmental biology is how cells interact to organize into tissues? In this paper, we study the role of mesenchyme-ectoderm interaction in the growing chick limb bud using Glazier and Graner's cellular Potts model, a grid-based stochastic framework designed to simulate cell interactions and movement. We simulate cellular mechanisms including cell adhesion, growth, and di...

Specification and determination (commitment) of positional identities precedes overt pattern formation during development. In the limb bud, it is clear that the anteroposterior axis is specified at a very early stage and is prepatterned by the mutually antagonistic interaction between Gli3 and Hand2. There is also evidence that the proximodistal axis is specified early and determined progressiv...

Introduction: Oxidative stress has been implicated in the pathogenesis of various diseases affecting chondrogenesis or the function of articular cartilage. The purpose of the present study was to find the effect of soybean extract on reduction of detoriation effects of oxidativestress in embryonic chondrogenesis in vitro. Methods: In order to separate ectoderm from mesenchyme, the limb buds ...

Hepatocyte growth factor/scatter factor (HGF/SF) stimulates proliferation, dissociation, migration and morphogenesis of cells in culture. To investigate a possible role for HGF/SF and its receptor, the Met tyrosine kinase, in embryonic development, we have analyzed their expression in mouse embryos from day 7.5 of gestation by whole-mount in situ hybridization. Met expression is first detected ...

We show here that bone morphogenetic protein 2 (BMP-2) is involved in patterning the developing chick limb. During early stages of limb development, mesenchymal expression of the Bmp-2 gene is restricted to the posterior part of the bud, in a domain that colocalizes with the polarizing region. The polarizing region is a group of cells at the posterior margin of the limb bud that can respecify t...

Expression of Sonic Hedgehog (Shh) in the posterior mesenchyme of the developing limb bud regulates patterning and growth of the developing limb by activation of the Hedgehog (Hh) signaling pathway. Through the analysis of Shh and Hh signaling target genes, it has been shown that activation in the limb bud mesoderm is required for normal limb development to occur. In contrast, it has been state...

Early in embryogenesis, precursors of the limb musculature are generated in the somite, migrate to the limb buds and undergo terminal differentiation. Although myogenic differentiation in culture is affected by several growth factors including fibroblast growth factor (FGF), it remains uncertain whether migration and differentiation of myogenic cells in vivo are directly regulated by such growt...