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Animal Growth and Development

Animal Growth and Development

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Animal Growth and Development

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  1. Animal Growth and Development

  2. What is the Different between Growth and Development??

  3. Introduction to animal development Animal Development • Development requires both cell growth and cell differentiation (different cells express different genes) How are new organisms produced?

  4. Fertilization • In mammals, sperm travel from the vagina to the fallopian tube • Fertilization takes place in the fallopian tube to form Zygote

  5. Once fertilization ends… What’s next?

  6. How many step happen in animal growth and development?

  7. TWO PHASES • Embryonic Phase • Pasca Embryonic Phase

  8. Egg and Zygote Polarity Most animals have eggs and zygote with polarity: Animal pole: low concentration of yolk. Vegetal pole: yolk concentrated here

  9. EMBRYONIC PHASE After fertilization…there are 3 major steps of embryonic phase: Morulation Blastulation Gastrulation Differentiation/ Organogenesis

  10. Stages of development Animal Embryonic Development 1. Early Cleavage (Morulation) • Cleavage begins within an hour of fertilization; series of mitotic divisions • Zygote divides into 2, 4, 8, … smaller and smaller blastomeres without increasing size of embryo • Cleavage involves about 12 divisions resulting in solid ball of blastomeres How are new organisms produced?

  11. In Amphibians • Completed in 24 hrs. • 1st and 2nd plane is meriodional; 3rd is equatorial • 16-64 cell stage – morula • 128 – 15,000 cell stage – blastula

  12. 2. Cleavage - blastulation rapid cell divisions little cell growth packaging of cytoplasmic heterogeneity final product is a hollow ball of cells = blastula cells = blastomeres hollow cavity = blastocoel

  13. Cont… yolky eggs alter pattern of divisions animal hemisphere divides normally vegetal (yolky) hemisphere divides less often produces larger cells amount of yolk affects cleavage pattern

  14. Gastrulation - sorts all the cells into distinct cell layers (ectoderm, endoderm, and mesoderm) Blastula (hollow ball of cells) transformed into the Gastrula (three layered stage) 3. Gastrulation

  15. 1. Gastrulation begins- Blastopore formed Blastopore - midway opening on one side of the blastula -Site of cell migration from the surface into the interior (Invagination) - Future site of anus Gastrulation

  16. 2. Cell migrating to form layers Archenteron – primitive gut formed (endoderm) future mouth Gastrulation

  17. 3.Gastrulation complete - Gastrula formed Endoderm and archenteron -replace the blastocoel Mesoderm - forms a layer between the ectoderm and endoderm Ectoderm- forms the outer layer. Yolk plug- (endoderm) marks the site of the blastopore and of the future anus Gastrulation

  18. Gastrulation in a sea urchin embryo Key Future ectoderm Future mesoderm Future endoderm Animalpole 1 The blastula consists of a single layer of ciliated cells surrounding the blastocoel. Gastrulation begins with the migration of mesenchyme cells from the vegetal pole into the blastocoel. Blastocoel Mesenchymecells Vegetalplate Vegetalpole The vegetal plate invaginates (buckles inward). Mesenchyme cells migrate throughout the blastocoel. 2 Blastocoel Filopodiapullingarchenterontip 3 Endoderm cells form the archenteron (future digestive tube). New mesenchyme cells at the tip of the tube begin to send out thin extensions (filopodia) toward the ectoderm cells of the blastocoel wall Archenteron Mesenchymecells Blastopore Blastocoel Contraction of these filopodia then drags the archenteron across the blastocoel. 4 50 µm Archenteron Ectoderm Blastopore Mouth 5 Fusion of the archenteron with the blastocoel wall completes formation of the digestive tube with a mouth and an anus. The gastrula has three germ layers and is covered with cilia, which function in swimming and feeding. Mesenchyme:(mesodermforms future skeleton) Digestive tube (endoderm) Anus (from blastopore)

  19. WATCH THIS VIDEO ….

  20. Differentiation/Organogenesis Changing process of structure and function become specific tissue. Formation of organ systems from germ layers

  21. Ectoderm • Makes up the outer covering of the gastrula • Becomes: • Nervous system • Epidermis

  22. Mesoderm • Becomes: • Muscles • Heart • Kidney • Dermis • Circulatory, urinary, reproductive system

  23. Endoderm • Becomes: • Digestive system • Respiratory System • Liver • Pancreas

  24. Pasca Embryonic Phase Maturity and Completing become more perfect organism. There are two divisions • Regeneration • Metamorphosis

  25. Repairing damage/lost organ. Eg. High Animal Asexual Reproduction. Eg. Planaria 1. Regeneration

  26. 1. Insect a. Ametabole NO metamorphosis - No Larva Stage - Increasing body size. Eg. Book Lice 2. METAMORPHOSIS

  27. Unperfect Metamorphosis. Stage: Egg  Larvae  semi-imago  imago/adult. Eg. Grasshopper Cockroach b. Hemimetabola

  28. Perfect Metamorphose Stage: Egg  Larvae (Instar) Pupae  Imago/Adult. Eg. Butterfly c. Holometabola

  29. 2. Amphibi • Premetamoprhosis Fertelized egg  Kecebong • Prometamorphosis Hind Limb appear and grow slowly. • Climax Metamorposis Front Limb appear and tail be lost

  30. Test yourself...