Post on 20-Jan-2016
Early Development Early Development
Selected InvertebratesSelected Invertebrates
CleavageCleavage
What characterizes this process?What characterizes this process?
CleavageCleavage
How does the cell cycle of blastomeres How does the cell cycle of blastomeres compare with that of somatic cells?compare with that of somatic cells?
CleavageCleavage
What happens to the embryo during What happens to the embryo during the mid-blastula transition?the mid-blastula transition?
When does this occur?When does this occur?
CleavageCleavage
What is karyokinesis and cytokinesis and What is karyokinesis and cytokinesis and how do they compare?how do they compare?
CleavageCleavage
What influences the pattern of What influences the pattern of cleavage in a particular organism?cleavage in a particular organism?
CleavageCleavage
CleavageCleavage
CleavageCleavage
How are cell fates specified during How are cell fates specified during cleavage?cleavage?– cell-cell interactionscell-cell interactions– asymmetric distribution of morphogenic asymmetric distribution of morphogenic
determinantsdeterminants
GastrulationGastrulation
What characterizes gastrulation in What characterizes gastrulation in organisms?organisms?
What kinds of movements occur?What kinds of movements occur?
Axis FormationAxis Formation
What are the three major body axes?What are the three major body axes?
Sea Urchin DevelopmentSea Urchin Development
What does the cleavage pattern look like?What does the cleavage pattern look like?
Sea Urchin DevelopmentSea Urchin Development
What characterizes the blastula stage?What characterizes the blastula stage?
Sea Urchin DevelopmentSea Urchin Development
At what stage are the fates of individual At what stage are the fates of individual cells determined?cells determined?
Sea Urchin DevelopmentSea Urchin Development
What role does What role does ββ--catenin play in catenin play in specification?specification?
Sea Urchin DevelopmentSea Urchin Development
Sea Urchin DevelopmentSea Urchin Development
When does axis specification occur?When does axis specification occur?– animal-vegetal axis established before animal-vegetal axis established before
fertilizationfertilization– anterior-posterior axis determined by a-anterior-posterior axis determined by a-
v axisv axis vegetal – determinants for posterior vegetal – determinants for posterior
developmentdevelopment
– dorsal-ventral and left-right after dorsal-ventral and left-right after fertilizationfertilization d-v by first cleavage planed-v by first cleavage plane
Sea Urchin DevelopmentSea Urchin Development
How does How does gastrulation begin?gastrulation begin?
Sea Urchin DevelopmentSea Urchin Development
What appears to be responsible for the What appears to be responsible for the ingression of primary mesenchyme?ingression of primary mesenchyme?
Sea Urchin DevelopmentSea Urchin Development
What appears to be responsible for the initial What appears to be responsible for the initial invagination that occurs during gastrulation?invagination that occurs during gastrulation?
Sea Urchin DevelopmentSea Urchin Development
What is the fate of these vegetal plate cells?
Sea Urchin DevelopmentSea Urchin Development
What happens during later stages of What happens during later stages of invagination?invagination?
Sea Urchin DevelopmentSea Urchin Development
Snail DevelopmentSnail Development
What kind of cleavage pattern What kind of cleavage pattern characterizes these animals?characterizes these animals?
Snail DevelopmentSnail Development
Orientation of Orientation of cleavage plane cleavage plane determines right or determines right or left coiling snailsleft coiling snails
Snail DevelopmentSnail Development
What appears to be responsible for the What appears to be responsible for the mosaic development seen in molluscs?mosaic development seen in molluscs?
Snail DevelopmentSnail Development What is the polar lobe and why is it important?What is the polar lobe and why is it important?
Snail DevelopmentSnail Development
Why does removal of the D blastomere Why does removal of the D blastomere or its first or second derivatives result in or its first or second derivatives result in incomplete larvae?incomplete larvae?
If D blastomeres don’t directly If D blastomeres don’t directly contribute cells to formation of many contribute cells to formation of many structures why are they so important to structures why are they so important to the formation of the same structures?the formation of the same structures?
Snail DevelopmentSnail Development
What other aspect of snail What other aspect of snail development does the polar lobe development does the polar lobe influence?influence?– How do we know this to be true?How do we know this to be true?
Snail DevelopmentSnail Development
How does gastrulation take place in snails?How does gastrulation take place in snails?
Tunicate DevelopmentTunicate Development
What makes these What makes these organisms rather organisms rather unique?unique?
What type of What type of cleavage pattern cleavage pattern do they have?do they have?
Tunicate DevelopmentTunicate Development
In what way does the pigmentation in In what way does the pigmentation in Styela partita Styela partita provide developmental provide developmental information?information?
Tunicate DevelopmentTunicate Development
What evidence is there of What evidence is there of autonomous specification in tunicate autonomous specification in tunicate blastomeres?blastomeres?– transplant experimentstransplant experiments– RNA hybridization experimentsRNA hybridization experiments– altering altering ββ-catenin levels in cells-catenin levels in cells
Tunicate DevelopmentTunicate Development
What evidence is there for What evidence is there for conditional specifiction?conditional specifiction?– BMP signal from endoderm induces BMP signal from endoderm induces
anterior cell to become notocordanterior cell to become notocord works through activation of works through activation of Brachury Brachury genegene
– FGF signal induces posterior cell to FGF signal induces posterior cell to become mesenchymebecome mesenchyme
Tunicate DevelopmentTunicate Development
When are the When are the embryonic axes embryonic axes established?established?– dorsal-ventral – dorsal-ventral –
prior to first prior to first cleavagecleavage
– anterior-posterior – anterior-posterior – prior to first prior to first cleavagecleavage
– left-right – first left-right – first cleavagecleavage
Tunicate Development Tunicate Development
What is What is gastrulation like in gastrulation like in these organisms?these organisms?
Caenorhabditis elegansCaenorhabditis elegans
What does What does C. elegansC. elegans look like? look like?
C. elegansC. elegans
What pattern of cleavage in seen in this What pattern of cleavage in seen in this nematode?nematode?
C. elegansC. elegans
C. elegansC. elegans
What determines What determines anterior-posterior anterior-posterior axis?axis?
What is the What is the importance of the importance of the P-granules?P-granules?
C. elegansC. elegans
When is dorsal-ventral and left-right axes When is dorsal-ventral and left-right axes established?established?
C. elegansC. elegans
In what way is autonomous In what way is autonomous specification demonstrated in this specification demonstrated in this organism?organism?– P1 develops without presence of AB cellP1 develops without presence of AB cell
In what way is conditional In what way is conditional specification demonstrated?specification demonstrated?– AB cell requires cell-cell interactionsAB cell requires cell-cell interactions– EMS requires signal from P2EMS requires signal from P2
C. elegansC. elegans
cell-cell signalingcell-cell signaling
C. elegansC. elegans
Where in this organism is Where in this organism is autonomous and conditional autonomous and conditional specification integrated?specification integrated?
C. elegansC. elegans
When does When does gastrulation begin gastrulation begin in this organism?in this organism?