Modules are like legos interactions are the different ways you can snap them

Modules are like legos interactions are the different

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Modules are like legos, interactions are the different ways you can snap them  together various different ways things can fit together and “work” Selection can then act on this variation since development is hierarchical w/ many stages/units/interactions   great  opportunity for change (descent w/ modification) Origins of Muscles
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the mesoderm along the central axis: segmented into  somites  by homeobox  ( Hox ) genes somites (paraxial mesodermal swellings) differentiate o dermomyotome:  on dorsal side   muscle, inner dermis myotome:  differentiates later to become muscle dermotome:  differentiates later to become inner dermis o sclerotome:  on ventral side   bone cartilage ALSO, the notochord below and ectoderm above the neural tube induce the  neural tube  to send out branches of cells o upper (dorsal) cells   sensory neurons o lower (ventral) cells   motor neurons in each somite, the myotome cells migrate laterally   bring w/ them their  bundle of sensory and motor nerves    muscles and nerves are integrated as  they migrate! How are muscles and nerves connected to the skeleton? sclerotomes  = vertebral cells;  connected tissue precursor cells o condese around notochord and neural tube sclerotome in each segment becomes a vertebra around the notochord  (which remains a gelatinous substance in the intervertebral discs For each segment of the body we have: a vertebra myotome to make muscles sensory and motor nerves
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myotome and sensory & motor nerves all travel together
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  • Spring '08
  • GeorgeV.Lauder,AndrewA.Biewener,PeterT.Ellison,andDanielE.Lieberman
  • Developmental Biology, Neural tube

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