- Spemann established the concept of organizer
- Until 1923, an embryo had a predefined “fate map”. Spemann proved that this was not the case
- Cells up to a certain stage are pluripotent – can have many developmental fates
- Stem cells and control over cell fate
Prospects - Spemann won the Nobel prize in 1935
- Hilde Mangold died in 1926…
- “Spemann Organizer” was found in all vertebrates, including human
- Dorsal-Ventral patterning has become the model system for embryonic patterning
- Stem cells are the promise for many future therapies
- summary
Molecular Basis of the Organizer - A gradient of morphogens determines the fate of the cells in the embryo.
- Morphpgen: A polypeptide that governs the development of a tissue
- Morphogens are produced from a defined source
- Their concentration provides positional information regarding the distance from the source
- The organizer secretes both morphogens and their inhibitors which diffuse throughout the embryo
- Ventral Lateral Dorsal
- (Organizer)
Molecular Basis of the Organizer - There are about 5 main families of morphogens used in all the developmental processes
- These families are shared by almost all multi-cellular organisms
- Drosophila uses the same morphogen as vertebrates to pattern its dorsal ventral axis
- But in the opposite direction
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