Animal Growth and Development

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Animal Growth and Development
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• What is the Different between Growth and
  Development??

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Animal Development

• Introduction to animal development

• Development requires both cell growth and cell
  differentiation (different cells express
  different genes)

How are new organisms produced?
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Fertilization

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

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Once fertilization ends

• Whats next?

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• How many step happen in animal growth and
  development?

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• TWO PHASES
• Embryonic Phase
• Pasca Embryonic Phase

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Egg and Zygote Polarity

• Most animals have eggs and zygote with polarity
• Animal pole low concentration of yolk.
• Vegetal pole yolk concentrated here

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EMBRYONIC PHASE After
fertilizationthere are 3 major steps of
embryonic phase

• Morulation
• Blastulation
• Gastrulation
• Differentiation/ Organogenesis

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Animal Embryonic Development

• Stages of 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?
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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

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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

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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

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3. Gastrulation

• 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)

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Gastrulation

• 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

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Gastrulation

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

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Gastrulation

• 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

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Gastrulation in a sea urchin embryo
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• WATCH THIS VIDEO .

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Differentiation/Organogenesis

• Changing process of structure and function become
  specific tissue.
• Formation of organ systems from germ layers

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Ectoderm

• Makes up the outer covering of the gastrula
• Becomes
• Nervous system
• Epidermis

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Mesoderm

• Becomes
• Muscles
• Heart
• Kidney
• Dermis
• Circulatory, urinary, reproductive system

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Endoderm

• Becomes
• Digestive system
• Respiratory System
• Liver
• Pancreas

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Pasca Embryonic Phase

• Maturity and Completing become more perfect
  organism.
• There are two divisions
• Regeneration
• Metamorphosis

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1. Regeneration

• Repairing damage/lost organ.
• Eg. High Animal
• Asexual Reproduction.
• Eg. Planaria

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2. METAMORPHOSIS

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

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b. Hemimetabola

• Unperfect Metamorphosis.
• Stage
• Egg ? Larvae ? semi-imago ? imago/adult.
• Eg. Grasshopper
• Cockroach

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c. Holometabola

• Perfect Metamorphose
• Stage
• Egg ? Larvae (Instar)? Pupae ? Imago/Adult.
• Eg. Butterfly

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2. Amphibi

• Premetamoprhosis
• Fertelized egg ? Kecebong
• Prometamorphosis
• Hind Limb appear and grow slowly.
• Climax Metamorposis
• Front Limb appear and tail be lost

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