1. Developmental Biology
An Understanding of Everything

2. Stages & Events of Chordate Embryogenesis
Developmental Process
Embryonic Stage
Zygote
Morula
Blastula
Gastrula
Neurulation
Fig. 8.2
Neurula
Pharyngula
Fetus

3. Process of producing gametes Spermatogenesis Oogenesis
Gametogenesis
Process of producing gametes
Spermatogenesis
Oogenesis
Meiotic cell division
Packaging of material into oocytes
Removal of cytoplasm from sperm

4. Accumulation of Vitellogenin during Oogenesis in Xenopus

5. Localization of Developmental Regulatory Factors
Dsh, Xcat-2, Xlsirt, Vg-1 mRNAs localized to vegetal pole of vertebrate eggs
Xlsirt mRNA

6. Bicoid Gradient in Drosophila Egg & Embryo
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7. Fertilization - Sperm and Egg Fusion
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8. Initial localization of material in eggs is radially symmetrical
Fertilization Induces a Rearrangement of Cytoplasmic, Localized Factors
Initial localization of material in eggs is radially symmetrical
Fertilization creates a point of asymmetry and causes rotational reorganization of cytoskeleton to generate bilateral symmetry
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Gray crescent

9. Reorganization of Cytoplasmic Maternal Factors Set Up Signaling Cascades
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10. Figure 20.12 Molecular Mechanisms of the Primary Embryonic Organizer
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11. Cleavage Distributes Maternal Components to Blastomeres
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12. Figure 19.7 Asymmetry in the Early Embryo (Part 1)
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13. Figure 19.7 Asymmetry in the Early Embryo (Part 2)
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14. Autonomous Development of Separated Tunicate Blastomeres

15. Figure 19.8 The Principle of Cytoplasmic Segregation
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16. Figure 20.10 Hans Spemann’s Early Experiments
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17. Figure 20.11 The Dorsal Lip Induces Embryonic Organization
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18. Fate Map of a Frog Blastula
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19. Figure 20.9 Gastrulation in the Frog Embryo (Part 1)
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20. Figure 20.9 Gastrulation in the Frog Embryo (Part 2)
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21. Figure 20.9 Gastrulation in the Frog Embryo (Part 3)
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22. Figure 20.15 Neurulation in the Frog Embryo (Part 1)
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23. Figure 20.15 Neurulation in the Frog Embryo (Part 2)
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24. Figure 20.13 Gastrulation in Amniotes (Part 1)
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25. Figure 20.13 Gastrulation in Amniotes (Part 2)
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26. Figure 20.16 The Development of Body Segmentation
Mouse embryo
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27. Drosophila Homeotic and Vertebrate Hox Genes Control A-P Patterning

28. Hox Genes Pattern A-P Axis

29. Concepts in Developmental Biology
Polarity
Established by localization of maternal gene products
Established by inductive signaling events
Morphogenesis
Cellular movements and embryonic structure formation
Regulated by cell-signaling & cell adhesion mechanisms
Differentiation
Specialization of cells to a particular fate
Growth
Increase in cell number
Increase in cell size

30. Occurs in multiple steps
Cell Specification
Differentiation
The process and the processes associated with a cell becoming specialized
Occurs in multiple steps

31. All differentiation information is contained within the cell
Cell Specification
Autonomous
All differentiation information is contained within the cell
Conditional
Differentiation information supplied through interactions with other cells

32. Cell Specification - Steps
Commitment
Specification
Determination
Terminal differentiation

33. Cell Specification - Commitment
A cell is said to be specified when:
Cells differentiate autonomously when removed from normal environment (embryo) and placed in a neutral environment (culture medium)
Placing cells into a non-neutral environment (a different place in the embryo) causes the cells to follow the fate of other cells the new location rather than their original fate

34. Cell Specification - Committment
Determination
A cell is said to be determined when:
Cells differentiate autonomously even when placed in a non-neutral environment
When moved to a different location within the embryo, the transplanted cells differentiate according to their original fate

35. Cell Specification - Terminal Differentiation
When a cell can no longer change or be changed into anything other than the cell type it is
Can be associated with permanent changes in DNA
DNA Methylation is a prominent factor
B-cells (plasma cells) rearrange the immunoglobulin (Ig) genes so that they can now only form a single type of Ig

36. Spemann’s Specification Experiments
Inductive signals trigger conditional specification, determination and differentiation
Presumptive neural plate ectoderm in the early gastrula was uncommitted. Later gastrula neuroectoderm was committed to a neural fate.

37. Dorsal Lip Transplantation

38. Reversal of Terminal Differentiation
Embryonic Stem cells
Totipotent or pluripotent cells
Dedifferentiated stem cells
Pluripotent
Derived from previously differentiated cells
Cloning proves nuclear equivalence

39. Figure 19.3 Cloning a Plant (Part 1)

40. Cloning by Nuclear Transplantation
Nuclear transplant experiments have shown that somatic cells contain the entire genome.
Nucleus of an unfertilized egg is replaced with the nucleus of a somatic cell
These experiments led to two important conclusions:
No information is lost in the early stages of embryonic development (a principle known as genomic equivalence).
The cytoplasmic environment around a nucleus can modify its fate.

41. The First Cloning Experiment – Nuclear Transplantation in Xenopus laevis
Cloning of the frog Xenopus laevis by nuclear transplantation of albino gut cell nuclei into enucleated, wt oocytes. All progeny are albino & female
tadpole
oocyte
nucleus

42. First Mammalian Clone

43. Dolly & Bonnie

44. Figure 19. 10 Induction during Vulval Development in C
Figure Induction during Vulval Development in C. elegans (Part 1)
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45. Figure 19. 10 Induction during Vulval Development in C
Figure Induction during Vulval Development in C. elegans (Part 2)
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46. A Gene Cascade Controls Pattern Formation in the Drosophila Embryo
Maternal effect genes
Gap genes
Pair rule genes
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Segment polarity genes
Homeotic genes

47. Bicoid and Nanos Protein Gradients Provide Positional Information (Part 1)
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48. Figure 19.14 Bicoid and Nanos Protein Gradients Provide Positional Information (Part 2)
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49. Figure 19.16 A Homeotic Mutation in Drosophila
Antennapedia
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50. Figure 19.12 Organ Identity Genes in Arabidopsis Flowers (Part 1)
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51. Figure 19.12 Organ Identity Genes in Arabidopsis Flowers (Part 2)
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52. Figure 19.13 A Nonflowering Mutant
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53. Northern Analysis: Gel
Electrophoresis
Formaldehyde gels
Methyl-mercury-OH gels

54. Northern Analysis: Probing
Spatial expression information

55. RNA Localization Developmental Stages
temporal expression information