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Signals in limb development: STOP, GO, STAY and POSITION
1Department of Anatomy and Developmental Biology, University College and Middlesex School of Medicine, London, UK.
Journal of Cell Science. Supplement
|January 1, 1990
Summary
Cell-to-cell communication guides early limb development through extracellular signals like STOP, GO, STAY, and POSITION. Limb patterning relies on these signals and cellular responses, influencing cartilage and pigment formation.
Area of Science:
- Developmental Biology
- Cell Signaling
- Extracellular Matrix Interactions
Background:
- Early limb development involves complex cell-to-cell interactions.
- Extracellular signals (STOP, GO, STAY, POSITION) regulate these interactions.
- Cellular responses to signals, rather than instructive signals themselves, drive developmental complexity.
Purpose of the Study:
- To analyze limb patterning within the framework of extracellular signaling.
- To investigate the role of positional signals and retinoic acid in anteroposterior axis specification.
- To explore signaling mechanisms independent of positional cues.
Main Methods:
- Analysis of extracellular signaling pathways in early limb bud development.
- Investigating the influence of mesenchyme and ectoderm signals on limb patterning.
- Examining the effects of growth factors on cartilage and muscle differentiation in vitro.
- Studying pigment pattern formation in relation to feather germ signaling.
Main Results:
- Limb patterning involves signals specifying positional values along anteroposterior axes, with retinoic acid as a potential morphogen.
- Evidence suggests patterning occurs independently of positional signals.
- Mesenchyme provides POSITION signals to the apical ridge; the ridge signals STAY to the progress zone mesenchyme.
- Non-ridge ectoderm signals STOP for cartilage differentiation, which is specified before condensation.
- Growth factors influence cartilage and muscle differentiation; feather germs signal STOP/GO to melanoblasts for pigment patterns.
Conclusions:
- Limb development is orchestrated by a complex interplay of extracellular signals and cellular responses.
- Specific signals (STOP, GO, STAY, POSITION) regulate distinct developmental processes like cartilage and pigment formation.
- The precise pathways for these cell-to-cell signals remain to be elucidated, with gap junctions as a potential mechanism.
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