Cellular adhesion is fundamental to the behaviour of cell populations during embryonic development and serves to establish correct tissue pattern and architecture. The cadherin superfamily of cell adhesion proteins regulates cellular organization and additionally influences intracellular signalling cascades. Here we present for the first time a detailed account of chick Fat-1 gene expression du...

The wing-bud shows zero regulation following removal of a whole slice of the proximal-distal axis from stage 22 or later. Prior to this it is possible that it may show some regulation. Some of the apparent regulation may be explained by the way in which the limb grows. The bud never shows perfect size regulation or morphallaxis. The proximal-distal axis of the bud between shoulder and wrist exp...

Here we report the isolation from a chick limb bud cDNA library of a cDNA that contains the full coding sequence of chicken Dlx-5, a member of the Distal-less (Din) family of homeobox-containing genes that encode homeodomains highly similar to that of the Drosophila Distal-less gene, a gene that is required for limb development in the Drosophila embryo. The expression pattern of Dlx-5 in the de...

Monoclonal antibody WE3 (mAb WE3) reacts to the majority of cells of the wound epithelium during limb regeneration, but to only a small minority of cells of skin epidermis. Since both the apical ectoderm of the limb bud and the wound epithelium of regenerating limbs are important to limb outgrowth, it was of interest to determine whether the WE3 antigen was shared by these two developmentally i...

During endochondral ossification in the vertebrate limb, multipotent mesenchymal cells first differentiate into chondroblasts (chondrogenesis) that further differentiate (via chondrocyte hypertrophy) to a terminal cellular phenotype. Dlx5 and Dlx6 are functionally redundant regulators of chondrocyte hypertrophy. We now show that Dlx5 and Dlx6 also regulate the earlier step of chondrogenesis in ...

Epithelial-mesenchymal feedback signaling is the key to diverse organogenetic processes such as limb bud development and branching morphogenesis in kidney and lung rudiments. This study establishes that the BMP antagonist gremlin (Grem1) is essential to initiate these epithelial-mesenchymal signaling interactions during limb and metanephric kidney organogenesis. A Grem1 null mutation in the mou...

We describe here how the early limb bud of the quail embryo develops in the absence of retinoids, including retinoic acid. Retinoid-deficient embryos develop to about stage 20/21, thus allowing patterns of early gene activity in the limb bud to be readily examined. Genes representing different aspects of limb polarity were analysed. Concerning the anteroposterior axis, Hoxb-8 was up-regulated a...

Bilateral innervation of a single hindlimb bud was induced by amputating the other limb bud and disrupting the barriers between the two sides. Though the routes of the crossed nerves were necessarily abnormal, the motor projections that developed subsequently were normal as determined by horseradish peroxidase tracing. The limb therefore appears to be innervated selectively, each region being i...

We examined systematically the ability of chick limb bud stumps to regenerate distal structures when fibroblast growth factor (FGF)-4 is applied. When amputations were made within 600 mu m of the tip and FGF-4 applied either posteriorly or both apically and posteriorly, outgrowth of stump tissues occurred and a virtually complete skeleton developed. 'Regeneration' of distal structures was corre...

The products of Hox-4 genes appear to encode position in developing vertebrate limbs. In chick embryos, a number of different signalling regions when grafted to wing buds lead to duplicated digit patterns. We grafted tissue from the equivalent regions in mouse embryos to chick wing buds and assayed expression of Hox-4 genes in both the mouse cells in the grafts and in the chick cells in the res...