How to ‘deconvolute’ lung evolution - vertebrate ontogeny - the ‘short history’ of evolution

Published on March 31, 2016   11 min

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Other Talks in the Series: Evolutionary Physiology

PROFESSOR JOHN TORDAY: Vertebrate ontogeny, the short history of evolution.
Ontogeny, or embryonic development, is the short history of the organism in contrast to phylogeny, which is the long history of the organism. Beginning with the fertilization of the egg by the sperm forming the zygote, cell-cell interactions dictate the patterning of the embryo to generate form and function. The cell-cell interactions are mediated by solute-secreted growth factors signaling to nearby cells that have specific cognate receptors for those growth factors. For example, fibroblast growth factor binds to the fibroblast growth factor receptor. The receptor then generates a second messenger that affects the growth and differentiation of the target cell. The target cell then generates a growth factor that acts on other cells within the region and so on and so on, until the entire organism is formed.
Here we see the fertilized egg or zygote on the left, progressively dividing and differentiating to form a two-layered blastula and then a three-layered gastrula composed of an ectoderm, endoderm, and mesoderm. From this stage on, the three germ layers form the embryo through the cell-cell growth factor signal.
On the left are depicted the interactions between the various components of developing bone, round chondrocytes, columnar chondrocytes, prehypertropic chondrocytes, hypertrophic chondrocytes, terminal hypertrophic chondrocytes, and trabecular bone. These different bone cell types interact through signaling, mediated by PTHrP, interacting with Indian hedgehog fibroblast growth factor, bone morphogenetic protein, notch, and the wingless int or Wnt pathway.

How to ‘deconvolute’ lung evolution - vertebrate ontogeny - the ‘short history’ of evolution

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