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OUTLINE 6 VI. Morphogenesis A. General features of gastrulation B. Cell movement 1. extension and contraction 2. adhesion C. Gastrulation in the sea urchin D. Gastrulation in the frog E. Three layers of cells 1. ectoderm 2. mesoderm 3. endoderm F. Neurulation
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animal pole vegetal pole
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After this point, Protostomes and Deuterostomes depart
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Echinoderms Chordates Arthropods Mollusks Annelids Protostomes Deuterostomes Acoelomates TIME
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Mouth develops: First Second Cleavage planes: Spiral Radial Early development: Not totipotent Totipotent
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EGG MORULA
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SEA URCHIN BLASTULA
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Fig 47.16
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Start of invagination (blastopore) Blastocoel Fig 47.9 Animal pole
Vegetal pole Start of invagination (blastopore)
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Fig 47.9 Archenteron
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Fig 47.9 Archenteron Mouth Digestive tract Anus
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Fig 47.9 Archenteron endoderm ectoderm mesoderm
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Fig 47.7
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Fig 47.7
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Fig 47.8 FROG BLASTULA
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Fig 47.10
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Frog blastula blastocoel Dorsal lip. The invagination for gastrulation starts here
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Fig 47.10
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Fig 47.10
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Fig 47.10
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Scanning Election Micrographs
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Fig Neurulation in the frog
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OUTLINE 7 VII. Mechanisms of Animal Development A. Cytoplasmic determinants 1. axes of symmetry in amphibians 2. bicoid gene in Drosophila B. Cell communication 1. Holtfreter’s work 2. mechanisms of cell recognition 3. induction C. Morphogens and pattern formation (chick limb bud) D. Hormones (in amphibian development) 1. pattern of metamorphosis 2. role of thyroxin 3. evidence
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ectoderm mesoderm endoderm 1. dissociation 3. resegregation 2. reaggregation Holtfretter 1955
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Spemann and Mangold: an organizer
Fig
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Pattern formation: the chick limb bud
Fig
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Pattern formation: the chick limb bud
Fig
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Tadpole Aquatic Gills Herbivorous Swimming Frog Terrestrial Lungs Carnivorous Jumping metamorphosis
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How do hormones turn on and off the genes that control development?
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Fig Development in the fly
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Fig Determination of anterior - posterior axis in the fly
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Natural variation in hormone levels can cause developmental plasticity
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Bigger is better! Pond dries, metamorphosis larger or death Size of
tadpole smaller Time
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Stage 36 O C Omnivore Carnivore 20 mm Stage 27 C O Stage 42 O C
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Comparison of beaks of spadefoot tadpoles
Omnivore Carnivore
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larger Size of tadpole smaller Time Pond dries, metamorphosis
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Natural and experimental variation in hormone levels can change the timing of development and metamorphosis: this provides an avenue for evolutionary innovation
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Evolution of Vertebrate body plan
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Amphioxus Larva Heterochrony Neoteny Paedomorphosis Adult
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Chemical pollutants can influence hormones and alter development
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Lake Apopka
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Concentration of toxins in water higher lower Lake Woodruff
Lake Apopka
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Lake Apopka larger smaller Lake Woodruff Alligator penis size
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Concentration of toxins in water
larger Alligator penis size smaller lower higher Concentration of toxins in water
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Effects of Atrazine on frog development
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