Summary of results
| . | Grafted site . | . | |
|---|---|---|---|
| Grafted material . | Flank . | Neck . | |
| Forelimb lateral mesoderm plus ectoderm | - Graft forms limb | - Graft forms limb | |
| - Graft recruits hosts lateral mesoderm into the limb | - Graft does not recruit host cells | ||
| Forelimb lateral mesoderm alone | - Graft signals to overlying host ectoderm and neighbouring host mesoderm and,together, they form a limb | - Graft forms small outgrowth, no limb | |
| - Graft triggers expression of dorsal limb ectoderm markers | |||
| - Graft does not trigger the Fgf-feedback loop required for limb bud initiation | |||
| Fgf10 bead | - Triggers MAPK signalling cascade in overlying ectoderm and induces AER/Fgf8 expression | - MAPK cascade not activated | |
| - No AER/Fgf8 expression | |||
| - Stimulates growth in mesoderm | - No Fgf-feedback loop | ||
| Result: establishment of Fgf-feedback loop, ectopic limb | - No ectopic limb | ||
| Fgf8 bead | - Triggers MAPK signalling in underlying mesoderm and stimulates Fgf10 expression | - Triggers MAPK cascade to the point of ERK1,2 phosphorylation | |
| Result: establishment of Fgf-feedback loop, ecotopic limb | - No Fgf-feedback loop | ||
| - No ectopic limb | |||
| . | Grafted site . | . | |
|---|---|---|---|
| Grafted material . | Flank . | Neck . | |
| Forelimb lateral mesoderm plus ectoderm | - Graft forms limb | - Graft forms limb | |
| - Graft recruits hosts lateral mesoderm into the limb | - Graft does not recruit host cells | ||
| Forelimb lateral mesoderm alone | - Graft signals to overlying host ectoderm and neighbouring host mesoderm and,together, they form a limb | - Graft forms small outgrowth, no limb | |
| - Graft triggers expression of dorsal limb ectoderm markers | |||
| - Graft does not trigger the Fgf-feedback loop required for limb bud initiation | |||
| Fgf10 bead | - Triggers MAPK signalling cascade in overlying ectoderm and induces AER/Fgf8 expression | - MAPK cascade not activated | |
| - No AER/Fgf8 expression | |||
| - Stimulates growth in mesoderm | - No Fgf-feedback loop | ||
| Result: establishment of Fgf-feedback loop, ectopic limb | - No ectopic limb | ||
| Fgf8 bead | - Triggers MAPK signalling in underlying mesoderm and stimulates Fgf10 expression | - Triggers MAPK cascade to the point of ERK1,2 phosphorylation | |
| Result: establishment of Fgf-feedback loop, ecotopic limb | - No Fgf-feedback loop | ||
| - No ectopic limb | |||