Adult stem cells provide replacement and repair descendants for normal turnover or injured tissues. These cells have been isolated and expanded in culture, and their use for therapeutic strategies requires technologies not yet perfected. In the 1970s, the embryonic chick limb bud mesenchymal cell culture system provided data on the differentiation of cartilage, bone, and muscle. In the 1980s, w...

Members of the fibroblast growth factor (FGF) family have been identified as signaling molecules in a variety of developmental processes, including important roles in limb bud initiation, growth and patterning. This paper reports the cloning and characterization of the chicken orthologues of fibroblast growth factor homologous factors-1 and -2 (cFHF-1/cFGF-12 and cFHF-2/cFGF-13, respectively). ...

Regeneration was studied in the Ambystoma annulatum by the amputation of the right forearm of twenty-four adults, over a twelve month period. Atthe termination of the experiment the limbs were reamputated 1-2 mm proximal to the original amputation site. The regenerated portions were staged, examined at the gross morphological level, and prepared for histological examination. Gross examination r...

Eph receptors and their ligands, the ephrins, have been implicated in early patterning and axon guidance in vertebrate embryos. Members of these families play pivotal roles in the formation of topographic maps in the central nervous system, the formation of brain commissures, and in the guidance of neural crest cells and motor axons through the anterior half of the somites. Here, we report a hi...

Recent studies have indicated that ATRA inhibits chondrogenesis and can lead to congenital clubfoot (CCF). The molecular mechanism of ATRA-induced chondrogenesis is not clear. As RhoA/ROCK and SDF-1/CXCR4 signaling play important molecular roles for a variety of cellular processes, we hypothesized that RhoA/ROCK2 and SDF-1/CXCR4 signaling are involved in ATRA-induced chondrogenesis in rat embry...

Axolotls (Ambystoma mexicanum) can completely regenerate lost limbs, whereas Xenopus laevis frogs cannot. During limb regeneration, a blastema is first formed at the amputation plane. It is thought that this regeneration blastema forms a limb by mechanisms similar to those of a developing embryonic limb bud. Furthermore, Xenopus laevis frogs can form a blastema after amputation; however, the bl...

We have addressed the problem of the segregation of cell lineages during the development of cartilage and muscle in the chick limb bud. The following experiments demonstrate that early limb buds consist of at least two independent subpopulations of committed precursor cells--those in (a) the myogenic and (b) the chondrogenic lineage-which can be physically separated. Cells obtained from stage 2...

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...