42 100 300 Somites set up central axis of body key role in segmentation of

42 100 300 somites set up central axis of body key

This preview shows page 42 - 55 out of 55 pages.

≈42 100-300!
Image of page 42
Somites set up central axis of body key role in segmentation of other parts of body
Image of page 43
neural tube (brain) heart (just beating) gut 1. Need a nervous system (folds into a tube) 2. Need segments 3. Need a gut and body cavity (other tubes) How do we get from 3 cell lines to something that looks like an organism? 4th week, ventral view
Image of page 44
The mesoderm lateral to the somites also differentiates Paraxial somites (vertebrae & associated muscles) Neural tube Intermediate (urogenital system) notochord Body wall Gut wall Circulatory system Limbs Lateral plate
Image of page 45
Splanchnic (gut) the story is a little tricky The lateral plate mesoderm splits into two layers: somatic (body) and splanchnic (gut) Paraxial Intermediate Lateral plate Somatic (body)
Image of page 46
Gut tube Neural tube THESE BEGIN TO FOLD AROUND THE FUTURE FRONT (VENTRAL) SIDE OF THE EMBRYO
Image of page 47
THESE FOLD AND MEET IN THE MIDLINE, FORMING A CENTRAL BODY CAVITY (COELOM*) *pronounced “seelom” COELOM* Gut tube Neural tube Paraxial mesoderm Splanchnic mesoderm Somatic mesoderm
Image of page 48
THE BODY CAVITY IS A USEFUL PLACE TO PUT ALL SORTS OF ORGANS…
Image of page 49
So, now, we have basically a segmented worm THIS IS THE BASIC BODY PLAN OF CHORDATES! Central nervous system Central axis Segmented body Gut
Image of page 50
Phylotypic stage Which is the fish, salamander, turtle, pig, dog, bird, monkey or human?
Image of page 51
fish s ala ma nd er turtl e bir d pig dog monkey human Phylotypic stage
Image of page 52
1. body is largely a set of folding tubes and sheets , each of which derives from three initial layers of cells REMEMBER THIS INTRODUCTORY STATEMENT? Three germ layers Tubes and sheets Simple embryo
Image of page 53
BUT, WE HAVE: limbs hair, milk Skeletons, heads All of these novelties are modifications of basic chordate plan! (next week) mammals reptiles amphibians fish lancelets
Image of page 54
10:00 MAC Steps ALL LEVELS WELCOME ESPECIALLY NON-RUNNERS! Come Run! SUNDAY!!!! How did evolution modify development of the basic body plan so that we got: NEXT LECTURE (Wednesday) - bones, muscles, nerves all connected - limbs - heads with big, complex brains
Image of page 55

You've reached the end of your free preview.

Want to read all 55 pages?

  • Fall '10
  • AndrewA.Biewener,PeterT.Ellison,andDanielE.Lieberman
  • Developmental Biology, Neural tube, Mesoderm, basic body plan

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture

Stuck? We have tutors online 24/7 who can help you get unstuck.
A+ icon
Ask Expert Tutors You can ask You can ask You can ask (will expire )
Answers in as fast as 15 minutes