Developmental Biology

Summary

• Vocabulary
• Embryo development is highly conserved in evolution
• Cells are not committed to a certain fate (pluripotent). They interact and influence each other and then specialize
• Dorsal ventral axis formation is a central model system for pattern formation

• Questions?

Cycle Length During Cleavage

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Choice of Model Organism

• Extra-cellular development
• T. teaniatus survives the grafting procedure
• T.cristatus has less pigmentation than T.teaniatus
• Similar species
• Though grafting between evolutionary distant organisms works as well

Experimental Procedures:

• Fertilization:
• Exert sperm (testes) and eggs.
• Manually fertilize in dish
• Graft
• Peel the Chorion off the two embryos
• Cut the receiving embryo where the graft will be inserted
• Excise the graft from the donating embryo
• Put the graft on the receiving embryo

• Medium
• Sterility
• “handle with care”

Grafting Experiments

• Graft region near the dorsal lip of T.cristatus (light) at gastrula and implant it in animal side of T.teaniatus/alpestris (dark) at gastrula.
• Fix the embryo at neurula, make cross sections, and characterize the resulting chimera

Controlled Experimental Variables

• Size of graft
• Exact location of graft from donor embryo
• Exact developmental stage of each embryo
• Graft location in the receiving embryo

Uncontrolled Experimental Variables

• Orientation of implant
• Embryo’s response to the procedure
• Contamination
• Embryo variation

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