4. Convergent extension

6. Triploblastic Our further gastrulation examples Flies

7. ~1000 cells Sea Urchin

9. Vade mecum …Movies Sea Urchin

10. Sea Urchin Ingression of primary mesenchymal cells

11. Primary mesenchyme is also called skeletogenic mesenchyme

12. Sea Urchin Receptors?

13. OTHER SUB-CLASS names for soluble ligand signals: (Further acting – through the bloodstream – endocrine) (Abutting cells – juxtacrine) (Cell release then re-uptake – autocrine) Communication between cells – comprehensively: 3 kinds of signal sources

14. Sea Urchin Hyaline ECM – basal lamina ECM – basal lamina: Chondroitin Sulfate Fibronectin Laminin Collagen

15. Sea Urchin

16. Vade mecum …Movies Sea Urchin

17. Sea Urchin – first stage of archenteron formation Also – changes in cytoskeleton of these cells -> cell shape changes

18. ~1000 cells Sea Urchin

19. Convergent extension Sea Urchin – second stage of archenteron formation

20. Sea Urchin – third stage of archenteron formation Secondary mesenchyme cells

21. Sea Urchin Nodal BMP-2/ BMP-4

23. ~1000 cells Sea Urchin

27. Skeletogenic micromeres: Beta Catenin (only autonomous cells) Sea Urchin

28. Figure 8.12(1) The Role of  -catenin in Specifying the Vegetal Cells of the Sea Urchin Embryo Remember the two apposing ‘organizers’ at the segment boundaries in Drosophila Armadillo is Beta-catenin

29. Disheveled expression in early Sea Urchin Embryos Disheveled (maternal, autonomous)

30. Figure 8.12(2) The Role of  -catenin in Specifying the Vegetal Cells of the Sea Urchin Embryo LiCl treatment (alters GSK-3 activ.)

31. Figure 8.12(3) The Role of  -catenin in Specifying the Vegetal Cells of the Sea Urchin Embryo

32. Figure 8.13 The Micromere Regulatory Network Proposed by Davidson and Colleagues (2002)

33. Figure 8.14(1) A Model of Endoderm Specification

34. ~1000 cells Sea Urchin Archenteron Blastocoel

35. Amphibian

38. earlyZfish| http://www.youtube.com/watch?v=moL5C8SjeJU zfish: http://www.youtube.com/watch?v=QXiFM2U1YFw frog: http://www.youtube.com/watch?v=8v6cXkzlEQA Frog gastrul/neurul: http://www.youtube.com/watch?v=qisrNX3QjUg&NR=1 Frog Inner Gast: http://www.youtube.com/watch?v=WSouNeWnZ_0 urchin longer: http://www.youtube.com/watch?v=AD4t5ijilYM&NR=1

39. Amphibian

43. Vade Mecum Amphibian

50. Figure 12.8(1) Movements of Cells During Secondary Neurulation in Xenopus

51. Figure 12.8(2) Movements of Cells During Secondary Neurulation in Xenopus

52. Amphibian