Embryogenesis of the chicks -------------اجنة 10

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Embryogenesis of the chicks -------------اجنة 10

  1. 1. Embryogenesis of the Chick The First 72 h Many of the embryonic images will be from: http://www.uoguelph.ca/zoology/devobio/dbindex.htm
  2. 2. Topics • Diapause • Gastrulation • Primitive Streak • Embryo @ 24 h • Embryo @48 h • Embryo @ 72 h • Hamburger-Hamilton Stages of Development
  3. 3. Diapause • Period of time between oviposition and incubation • Physical Egg Conditions, –Embryo & Cell Division –Storage Conditions –Turkey Eggs
  4. 4. Gastrulation in a Microlecithal Egg QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. Images from: http://www.uoguelph.ca/zoology/devobio/210labs/gastrulation1.html QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. blue=Ectoderm red=Mesoderm yellow=Endoderm AP=Animal Pole; VP=vegetal
  5. 5. Gastrulation in the Chicken
  6. 6. Gastrulation in the Chicken, cont.
  7. 7. Gastrulation in the Chicken, cont.
  8. 8. a. All embryonic layers originate from Epiblast b. At gastrulation, cells from Epiblast migrate down between Epiblast & Hypoblast c. Presumptive Mesodermal cells remain between Epiblast & Hypoblast d. Presumptive Endoderm formed by cells migrating down into Hypoblast Primary Germ layer Completion
  9. 9. Gastrulation in the Chicken, cont.
  10. 10. Epiblast gives rise to all 3 Germ Layers
  11. 11. Where do Cells on the Surface of the Blastoderm end up (in Germ Layers) Presumptive areas studied by; 1. Marking with Dye a. India Ink injection dye picked up by cells b. Radioisotope labeling of an embryo c. Transplantation of labeled blastoderm
  12. 12. Primary Embryonic Tissue Layers • What types of tissues and organs result from the formation of the Ectoderm; Mesoderm; and Ento/Endoderm?
  13. 13. 24 h Embryo
  14. 14. 33 h Developments • Erythrocytes form in extraembryonic mesoderm, • Appear in patches, blood islets/islands (BI) • BI’s caudal to the embryo • Peripheral cells of BI aggregates form endothelium that constitute walls of the blood vessel • Blood vessels constitute vitelline blood supply, extra vascular blood supply • Heart formation is occurring
  15. 15. 33 h Embryo
  16. 16. 48 h Embryo
  17. 17. 72 h Embryo 1 = Telencephalon 2 = Diencephalon 3 = Mesencephalon 4 = Metencephalon 5 = Myelencephalon * = Otic capsule ^ = Olfactory pit
  18. 18. Staging Embryos, Hamburger Hamilton Stages

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