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Biology 624 - Developmental Genetics

Biology 624 - Developmental Genetics. Lecture #4 – Gastrulation Movements. GASTRULATION is a complex series of cell movements that: --rearranges cells, giving them new neighbors

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Biology 624 - Developmental Genetics

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  1. Biology 624 - Developmental Genetics Lecture #4 – GastrulationMovements

  2. GASTRULATION is a complex series of cell movements that: --rearranges cells, giving them new neighbors --results in the formation of 3 GERM LAYERS that will form the subsequent embryo: ectoderm, endoderm and mesoderm --forms the main body axes of the embryo (they were specified earlier but not formed)

  3. * cleavage organogenesis GASTRULATION 16h 1.5h 0h 6h * organogenesis cleavage GASTRULATION dorsal closure * cleavage 2.5h GASTRULATION neurulation organogenesis 24h * 0h 10h GASTRULATION cleavage * segmentation organogenesis * GASTRULATION GASTRULATION 3.5h first cleavage implantation organogenesis cleavage organogenesis 18h 2.8h segmentation segmentation 5h 10h 24h 24h 24h 14d 20d 48-72h 21d 4.5d 6.5d 4d 7d 36h

  4. Invagination- the infolding of a region of cells

  5. Involution- the inturning of an expanding outer layer of cells

  6. Ingression- the migration of individual cells from surface to interior

  7. Delamination- the splitting of one sheet of cells into two parallel sheets of cells

  8. Epiboly- the movement of epithelial sheets that spread as a unit to cover the embryo

  9. Convergent Extension Convergent extension- the lengthening of a group of cells in the long axis while shortening in the perpendicular axis

  10. Cell Movements during Convergent Extension in Zebrafish

  11. Fate map of the fly embryo at cellular blastoderm stage

  12. Early Gastrulation in Drosophila

  13. Figure 9.40 Gastrulation in Drosophila

  14. Schematic Representation of Mid-Gastrulation in Drosophila

  15. Germ Band Extension in Drosophila

  16. GERM BAND EXTENDED PROCESSES: --organogenesis – e.g. nervous system forms by neuroblastingression from ectoderm --segmentation – A-P segment unique identity set up --imaginal disc specification – cells set aside that will survive pupation

  17. Germ Band Retraction in Drosophila

  18. Gastrulation in Drosophila - lateral view

  19. Gastrulation in Drosophila– Vade Mecum Movie

  20. FGF Signaling is Critical to Gastrulation in Drosophila Stage 7 Stage 8 Stage 9 WildType Mutant early gastrulation mid- gastrulation extended germ band Neurotactin, membrane marker Twist, mesoderm marker (Gryzik and Muller, 2004)

  21. Model for FGF signaling in Drosophila gastrulation (Leptin and Affolter, 2004)

  22. Fate Map of the Blastula of the Frog Xenopus laevis

  23. Cell Movements During Frog Gastrulation - Early

  24. Cell Movements During Frog Gastrulation - Mid

  25. Cell Movements During Frog Gastrulation - Late

  26. Epiboly of the Ectoderm Is Accomplished by Cell Division and Intercalation

  27. Convergent Extension Convergent extension- the lengthening of a group of cells in the long axis while shortening in the perpendicular axis

  28. Movie of Xenopus Gastrulation

  29. Xenopus Gastrulation – Vade Mecum

  30. Fibronectin and Amphibian Gastrulation Normal FN block peptides

  31. Blastocoel Roof Explants deposit matrix that directs the migration of mesoderm from Nagel et al, 2004

  32. FGF Expression during avian gastrulation and the putative role of Sprouty/spred from Keller, 2005

  33. Convergent Extension Tissue Separation Wnt Signaling Mediates Two Distinct Aspects of Gastrulation (Huelsken and Birchmeier, 2001)

  34. Amphibian Convergence Extension Requires Non-canonical Wnt Signaling (Habas et al, 2003)

  35. CE in Zebrafish Requires Oriented Cell Division This is the dorsal ectoderm of embryos in gastrulation, Xdd is a Disheveled mt, animal pole is up (Gong et al, 2004)

  36. papc Expression is Defective in spt Mutant Embryos WT spt-

  37. At the end of gastrulation-- --the basic body plan is set up --the three germ layers have formed and will produce all embryonic structures except the germline

  38. ECTODERM-- --skin, nervous system, neural crest MESODERM-- --muscle, bones, blood and vessels, kidney, gonads, connective tissue ENDODERM-- --gut, liver, lungs, pancreas

  39. * cleavage GASTRULATION organogenesis 0h 1.5h 6h 16h C. elegans embryogenesis

  40. * organogenesis cleavage GASTRULATION dorsal closure 0h 2.5h 10h 24h Drosophila embryogenesis

  41. * cleavage GASTRULATION neurulation organogenesis 3.5h 18h Frog embryogenesis 36h

  42. * GASTRULATION cleavage segmentation organogenesis 2.8h 5h 10h 24h 48-72h Zebrafish embryogenesis

  43. Egg laid * GASTRULATION cleavage organogenesis segmentation 21d 24h 4d 7d Chick embryogenesis

  44. * GASTRULATION first cleavage implantation organogenesis segmentation 14d 20d 24h 4.5d 6.5d Mouse embryogenesis

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