Approaches to Developmental Biology

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Approaches to Developmental Biology
1. Anatomical 2. Experimental 3. Genetic
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Anatomical approaches

• Comparative embryology
• Evolutionary embryology
• Teratology
• Mathematical modeling

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Comparative embryology
Aristotle Oviparity birds, frogs, most
invertebrates Viviparity placental
mammals Ovoviviparity certain reptiles,
sharks
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Comparative embryology
Harvey Ex ovo omnia Blastoderm
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Marcello Malpighi Introduction of
microscopes He could observe structural details
in unincubated chicken eggs. Epigenesis Prefo
rmation
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Preformation All structures are prefigured in
the germ cells. Fit well with the religious and
scientific thought of Seventeenth century.
Wolff Intestine, heart and blood Genetic
variations
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Blumenbach Regeneration in Hydra developmental
force Left-coiled snails can produce
right-coiled progeny
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Pander, Ernst von Baer and Heinrich Rathke
The germ layers

• Ectoderm outermost layer of the embryo
• Brain, Nerve cells, surface layer of skin
• 2. Mesoderm middle
• Heart, Blood, Kidney, Gonads, Bone
• 3. Endoderm inner
• Intestine, lung
• Induction Interaction among these layers
  produce many organs laid preformation to rest

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Von Baers four principles

• General features of a large group appear earlier
  than specialized features of smaller group.
• All vertebrate embryos have gill arches,
  notochords, spinal cords, and primitive
  kidneys.2. Less general characters develop from
  more general.
• Skin development in vertebrates.
• 3. Embryo of a given species, instead of
  passing through the adult stages of lower
  animals, departs more and more from them.
• 4. Early embryo of a higher animal is not like a
  lower animal, but like its early embryo.

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Chicken
Salamander
Fish
Human
Marsupial
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Fate mapping
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Fate mapping
Direct observation Conklin and tunicate embryo
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Fate mapping
Direct observation Conklin and tunicate embryo
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Fate mapping
Vital dye marking Vogt and amphibian eggs
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Fate mapping
Radio-labelling Rosenquist and chicken embryo
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Fate mapping
Fluorscent-labelling Fate mapping in zebra
fish
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Fate mapping
Genetic marking Chicken and quail chimeric
embryos
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Fate mapping
Genetic marking Neural crest cell migration