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Ch. 47—Animal Development. Fertilization. Fertilization. Fertilization. Fertilization. Once fertilization is complete. Animal Development. Cleavage —rapid mitotic cell division into smaller cells— blastomeres Solid ball of cells— morula - PowerPoint PPT Presentation
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Ch. 47—Animal Development
Fertilization
Fertilization
Fertilization
Fertilization
Once fertilization is complete
Animal Development
• Cleavage—rapid mitotic cell division into smaller cells—blastomeres
• Solid ball of cells—morula• Blastula produced when a
cavity called blastocoel forms
• Gastrulation—rearrangement of cells into 3 germ layers
blastomeres
Morula (solid ball of cells)
Blastocyst• Blastula stage of
mammalian embryos• Trophoblast layer
enclosing the blastocoel– Chorion (outer
embryonic layer)
Blastocyst develops into gastrula
Gastrulation• Cells rearrange and fold inward at the blastopore to form a gastrula with three-germ layers:– Ectoderm (skin, nails, teeth)– Mesoderm (skeletal, muscular, excretory, circulatory, reproductive
systems; blood, bone, and muscle)– Endoderm (epithelial lining of digestive, respiratory, excretory
tracts; liver, pancreas)
Organogenesis• Development of 3 germ
layers into the beginnings of organs– Notochord—stiff dorsal
skeletal rod (from mesoderm)– Neural plate—will become
brain and spinal cord (from ectoderm)
– Somites—blocks of mesoderm arranged along notochord; sign of segmentation
Amniotes• Amnion—fluid filled cavity; protects embryo• Allantois—disposal sac• Chorion—exchange gases• Yolk sac—provides nutrients
Eutherian mammals