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Early Development

Early Development . Selected Invertebrates. Cleavage. What characterizes this process?. Cleavage. How does the cell cycle of blastomeres compare with that of somatic cells?. Cleavage. What happens to the embryo during the mid-blastula transition? When does this occur?. Cleavage.

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Early Development

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  1. Early Development Selected Invertebrates

  2. Cleavage • What characterizes this process?

  3. Cleavage • How does the cell cycle of blastomeres compare with that of somatic cells?

  4. Cleavage • What happens to the embryo during the mid-blastula transition? • When does this occur?

  5. Cleavage • What is karyokinesis and cytokinesis and how do they compare?

  6. Cleavage • What influences the pattern of cleavage in a particular organism?

  7. Cleavage

  8. Cleavage

  9. Cleavage • How are cell fates specified during cleavage? • cell-cell interactions • asymmetric distribution of morphogenic determinants

  10. Gastrulation • What characterizes gastrulation in organisms? • What kinds of movements occur?

  11. Axis Formation • What are the three major body axes?

  12. Sea Urchin Development • What does the cleavage pattern look like?

  13. Sea Urchin Development • What characterizes the blastula stage?

  14. Sea Urchin Development • At what stage are the fates of individual cells determined?

  15. Sea Urchin Development • What role does β-catenin play in specification?

  16. Sea Urchin Development

  17. Sea Urchin Development • When does axis specification occur? • animal-vegetal axis established before fertilization • anterior-posterior axis determined by a-v axis • vegetal – determinants for posterior development • dorsal-ventral and left-right after fertilization • d-v by first cleavage plane

  18. Sea Urchin Development • How does gastrulation begin?

  19. Sea Urchin Development • What appears to be responsible for the ingression of primary mesenchyme?

  20. Sea Urchin Development • What appears to be responsible for the initial invagination that occurs during gastrulation?

  21. Sea Urchin Development What is the fate of these vegetal plate cells?

  22. Sea Urchin Development • What happens during later stages of invagination?

  23. Sea Urchin Development

  24. Snail Development • What kind of cleavage pattern characterizes these animals?

  25. Snail Development • Orientation of cleavage plane determines right or left coiling snails

  26. Snail Development • What appears to be responsible for the mosaic development seen in molluscs?

  27. Snail Development • What is the polar lobe and why is it important?

  28. Snail Development • Why does removal of the D blastomere or its first or second derivatives result in incomplete larvae? • If D blastomeres don’t directly contribute cells to formation of many structures why are they so important to the formation of the same structures?

  29. Snail Development • What other aspect of snail development does the polar lobe influence? • How do we know this to be true?

  30. Snail Development • How does gastrulation take place in snails?

  31. Tunicate Development • What makes these organisms rather unique? • What type of cleavage pattern do they have?

  32. Tunicate Development • In what way does the pigmentation in Styela partita provide developmental information?

  33. Tunicate Development • What evidence is there of autonomous specification in tunicate blastomeres? • transplant experiments • RNA hybridization experiments • altering β-catenin levels in cells

  34. Tunicate Development • What evidence is there for conditional specifiction? • BMP signal from endoderm induces anterior cell to become notocord • works through activation of Brachury gene • FGF signal induces posterior cell to become mesenchyme

  35. Tunicate Development • When are the embryonic axes established? • dorsal-ventral – prior to first cleavage • anterior-posterior – prior to first cleavage • left-right – first cleavage

  36. Tunicate Development • What is gastrulation like in these organisms?

  37. Caenorhabditis elegans • What does C. elegans look like?

  38. C. elegans • What pattern of cleavage in seen in this nematode?

  39. C. elegans

  40. C. elegans • What determines anterior-posterior axis? • What is the importance of the P-granules?

  41. C. elegans • When is dorsal-ventral and left-right axes established?

  42. C. elegans • In what way is autonomous specification demonstrated in this organism? • P1 develops without presence of AB cell • In what way is conditional specification demonstrated? • AB cell requires cell-cell interactions • EMS requires signal from P2

  43. C. elegans • cell-cell signaling

  44. C. elegans • Where in this organism is autonomous and conditional specification integrated?

  45. C. elegans • When does gastrulation begin in this organism?

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