Embryology and Body Cavities Lecture 3. Tissue Development Zygote (fertilized egg) undergoes rapid...
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Transcript of Embryology and Body Cavities Lecture 3. Tissue Development Zygote (fertilized egg) undergoes rapid...
![Page 1: Embryology and Body Cavities Lecture 3. Tissue Development Zygote (fertilized egg) undergoes rapid cell divisions called cleavage Forms a hollow ball.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649eca5503460f94bd91e2/html5/thumbnails/1.jpg)
Embryology and Body Cavities
Lecture 3
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Tissue Development• Zygote (fertilized egg) undergoes rapid cell
divisions called cleavage• Forms a hollow ball of cells called the
blastula
Blastula
![Page 3: Embryology and Body Cavities Lecture 3. Tissue Development Zygote (fertilized egg) undergoes rapid cell divisions called cleavage Forms a hollow ball.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649eca5503460f94bd91e2/html5/thumbnails/3.jpg)
Tissue Development Continued• The blastula
INVAGINATES (folds inward at one point)• Called Gastrulation• The opening is called
the blastopore• The center is the
primitive gut or Archenteron blastopore
Archenteron
Gastrula
![Page 4: Embryology and Body Cavities Lecture 3. Tissue Development Zygote (fertilized egg) undergoes rapid cell divisions called cleavage Forms a hollow ball.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649eca5503460f94bd91e2/html5/thumbnails/4.jpg)
Embryonic Development
![Page 5: Embryology and Body Cavities Lecture 3. Tissue Development Zygote (fertilized egg) undergoes rapid cell divisions called cleavage Forms a hollow ball.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649eca5503460f94bd91e2/html5/thumbnails/5.jpg)
Tissue Development• Protostomes-mouth forms from
blastopore–Mollusks, Annelids, Arthropods
• Deuterostomes- anus forms from blastopore–Echinodermata, Chordata
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Germ Layers• Germ layers forms tissues, organs, and
systems
• 3 Types of Germ Layers1. Ectoderm2. Mesoderm3. Endoderm
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3 Germ Layers1. Ectoderm- outer most layer– Gives rise to: • Epidermis (skin)• Nervous system
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• 2. Mesoderm-middle layer–Gives rise to:•Muscles•Skeleton•Blood System
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• Endoderm- inner most layer–Gives rise to:•Digestive Organs•Lungs•Bladder
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![Page 11: Embryology and Body Cavities Lecture 3. Tissue Development Zygote (fertilized egg) undergoes rapid cell divisions called cleavage Forms a hollow ball.](https://reader035.fdocuments.in/reader035/viewer/2022062409/56649eca5503460f94bd91e2/html5/thumbnails/11.jpg)
Three Types of Organisms1. Multicellular-have no tissue layers at all–Sponges
2. Diploblastic-have only Ectoderm and Endoderm–Cnidarians (jellyfish, sea anemones)
3. Triploblastic-have all three layers–Mollusks, arthropods, echinoderms,
chordates, etc.
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Benefit of Having a Body Cavity?
• Provides room for organ development• Provides more surface area for
gas exchange and nutrient absorption• Provides for storage area
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Benefits Cont’d
• Can act as a hydrostatic skeleton• Allows for waste removal• Allows for increased body size
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Triploblastic Organisms
• Have three Coelom (body cavity) patterns–Acoelomate–Pseudocoelomate–Coelomate
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Acoelomates
• Have a solid mass of Mesoderm cells between the Endoderm and Ectoderm layers• Ex. Flatworms
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Pseudocoelomates
• The cavity is not entirely lined by mesoderm• Ex. Nematode (worm)
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Coelomates
• The body cavity is completely surrounded by mesoderm.• Ex. Human
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Triploblastic Body Plans
Acoelomate Pseudocoelomate Coelomate