Developmental Biology


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Bog'liq
The Spemann experiment

Spemann’s innovation

  • 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
  • Morphogen
  • concentration
  • heart
  • kidney
  • muscle
  • nerves
  • 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
  • Morphogen
  • concentration
  • heart
  • kidney
  • muscle
  • neural chord
  • Ventral Lateral Dorsal
  • Vertebrates
  • Drosophila

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