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Hensen's node provides an endogenous limb-forming signal
1Department of Anatomy, University of Connecticut Health Center, Farmington, Connecticut 06030, USA.
Developmental Biology
|August 15, 1997
Summary
Hensen's node grafts can induce rudimentary limb formation in chick embryos, forming structures resembling limb segments. However, these induced limbs are incomplete, lacking proper patterning and specific gene expression crucial for full development.
Area of Science:
- Developmental Biology
- Embryology
- Molecular Biology
Background:
- Limb development in chick embryos involves a signaling cascade from Hensen's node to lateral plate mesoderm.
- The precise signals and their roles in limb patterning are not fully understood.
Purpose of the Study:
- To investigate the role of Hensen's node in inducing limb formation.
- To identify the molecular signals involved in Hensen's node-induced limb development.
Main Methods:
- Grafting Hensen's node onto the flank region of stage 9-15 chick embryos.
- Analyzing the morphology and gene expression (Msx-2, BMP-4, sonic hedgehog, FGF-4, FGF-8) of induced structures.
Main Results:
- Hensen's node grafts induced supernumerary, rudimentary limbs with segmented cartilage resembling stylopod, zeugopod, and autopod.
- Induced limbs expressed limb-characteristic genes Msx-2 and BMP-4.
- Induced limbs were incomplete, lacking girdles, paired elements, and expression of patterning genes (sonic hedgehog, FGF-4, FGF-8).
Conclusions:
- Hensen's node provides an initial limb-forming signal to the lateral mesoderm.
- Additional signals are required for complete limb patterning, morphogenesis, and expression of key developmental genes.