Endoderm and primary induction

1. Endoderm and primary induction

13. Figure 1.6 Fate Maps of Different Vertebrate Classes at the Early Gastrula Stage

14. Figure 1.5 The Similarities and Differences among Different Vertebrate Embryos

15. START PRIMARYORGANIZERLECTURE FROM HERE

16. Terms (definitions) for Establishment of cells and tissues(here use lens cells as an example) • Competence, wherein cells can become lens precursors if they are exposed to the appropriate combination of signals. • Specification, wherein cells have received the appropriate signals to become lens precursors, but progression along the pathway to lens can still be repressed by other signals. • Commmitment (determination), wherein lens precursors have entered a differentiation pathway, and will become lens even in the presence of inhibitory signals. • Differentiation, wherein the lens cells leave the mitotic cycle and express those genes characteristic of their cell type.

18. Early dpp/BMP gradients dictate the D/V axis of the entire embryo

19. Early dpp/BMP gradients dictate the D/V axis of the entire embryo Figure 23.14 Homologous Pathways Specifying Neural Ectoderm in Protostomes (Drosophila) and Deuterostomes (Xenopus) D/V

20. Later cases of dpp/BMP expression direct specific embryonic tissue inductions

21. Later cases of dpp/BMP expression direct specific embryonic tissue inductions

22. Later cases of dpp/BMP expression direct specific embryonic tissue inductions

23. Later cases of dpp/BMP expression direct specific embryonic tissue inductions Sea Urchin BMP-2/ BMP-4 Nodal

25. Figure 3.14 Roux’s Attempt to Demonstrate Mosaic Development Wilhelm Roux, 1888

26. Figure 3.15 Driesch’s Demonstration of Regulative Development Hans Drriesch, 1892

27. Figure 3.12 In the Early Developmental Stages of Many Vertebrates, the Separation of the Embryonic Cells Can Create Twins - Armadillo

28. Figure 1.7(1) Fate Map of the Tunicate Embryo

30. Figure 3.8 Autonomous Specification in the Early Tunicate Embryo

31. Acetylcholinesterase in the Progeny of the Muscle Lineage Blastomeres

32. Figure 3.10 Microsurgery on Tunicate Eggs

33. Figure 3.11 Conditional Specification

35. Two critical inductions: Formation of the primary organizer Action of the primary organizer

40. Neurulation is induced (By the ‘primary organizer’)

41. -1. The primary organizer induces neurulation and axis formation -2. The primary organizer itself arises from a previous induction

42. -1. The primary organizer induces neurulation and axis formation -The dorsal lip of the blastopore contains the primary organizer

43. -1. The primary organizer induces neurulation and axis formation -The dorsal lip of the blastopore contains the primary organizer

44. -1. The primary organizer induces neurulation and axis formation -The dorsal lip of the blastopore contains the primary organizer

45. -1. The primary organizer induces neurulation and axis formation Figure 10.21(1) Organization of a Secondary Axis by Dorsal Blastopore Lip Tissue

46. -1. The primary organizer induces neurulation and axis formation Figure 10.21(1) Organization of a Secondary Axis by Dorsal Blastopore Lip Tissue

48. Amphibian

49. -1. The primary organizer induces neurulation and axis formation Source of primary organizer shown on fate map Amphibian

50. -The primary organizer induces neurulation and axis formation -The primary organizer itself arises from a previous induction