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

21
mbryogenesis of the Chi The First 72 h Many of the embryonic images will be from: http://www.uoguelph.ca/zoology/devobio/d

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

Page 1: Embryogenesis of the chicks -------------اجنة 10

Embryogenesis of the ChickThe First 72 h

Many of the embryonic images will be from: http://www.uoguelph.ca/zoology/devobio/dbindex.htm

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Topics• Diapause• Gastrulation• Primitive Streak• Embryo @ 24 h• Embryo @48 h• Embryo @ 72 h• Hamburger-Hamilton Stages of

Development

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Diapause

• Period of time between oviposition and incubation

• Physical Egg Conditions, – Embryo & Cell Division

– Storage Conditions

– Turkey Eggs

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Gastrulation in a Microlecithal Egg

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Images from: http://www.uoguelph.ca/zoology/devobio/210labs/gastrulation1.html

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blue=Ectoderm red=Mesoderm yellow=Endoderm

AP=Animal Pole; VP=vegetal

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Gastrulation in the Chicken

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Gastrulation in the Chicken, cont.

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Gastrulation in the Chicken, cont.

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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

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Gastrulation in the Chicken, cont.

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Epiblast gives rise to all 3 Germ Layers

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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 injectiondye picked up by cells

b. Radioisotope labeling of an embryo

c. Transplantation of labeled blastoderm

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Primary Embryonic Tissue Layers

• What types of tissues and organs result from the formation of the Ectoderm; Mesoderm; and Ento/Endoderm?

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24 h Embryo

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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

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33 h Embryo

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48 h Embryo

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72 h Embryo

1 = Telencephalon

2 = Diencephalon

3 = Mesencephalon

4 = Metencephalon

5 = Myelencephalon

* = Otic capsule

^ = Olfactory pit

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Staging Embryos,

Hamburger Hamilton Stages

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