BIO 302 Lecture Notes - Lecture 4: Optic Vesicle, Neural Tube, Germinal Disc
Axis determination in chick: Gravity: how oocyte moves through oviduct
Top is posterior:
Cleavage occurs just through the blastodisc
Yolk
• Epiblast
o Meso
o Endo
o Ect
o Amnion
• Hyperblast
o Extraembryonic membrane
Early mammalian development slower than birds. Cleavage happens in 1 week v.s 1 day.
One cell or group of cells - the inducer - signals to another cell or group - the responder
The responder must be competent to receive the signal - only some cells are able to respond to
a given signal.
Patterning neurulation early events
• How does neural become different from epidermal
1. Organizer secretes a ‘ neurulizing factor ‘ that causes cells to form nervous tissues
2. Organizer secretes a factor that neutralizes instructions to make epidermis, so neural is
the default condition.
How does the neural tube get patterned dorso-ventrally?
• Gene families - 2 kinds of molecules especially important for developmental patterns
o Signaling: ligands and receptors
o BMP’s:
• Dorsoventral patterning of the neural tube:
o Morphogen gradients again
o Shh ventral-dorsal
o TGF -(BMP’s) dorsal-ventral
Many developmental problems are due to improper closure of the neural tube
1. Cell differentiation?
2. How do they follow certain pathways
Best definition of induction:
-One cell or part of an embryo influencing the development of another
What would you predict will happen if you transplant the optic vesicle to a different place under
the ectoderm?
-The lens will either not form or form in a different place if you transplant the optic vesicle to
another place
find more resources at oneclass.com
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Document Summary
Axis determination in chick: gravity: how oocyte moves through oviduct. Yolk: epiblast, meso, endo, ect, amnion, hyperblast, extraembryonic membrane. Cleavage happens in 1 week v. s 1 day. One cell or group of cells - the inducer - signals to another cell or group - the responder. The responder must be competent to receive the signal - only some cells are able to respond to a given signal. Many developmental problems are due to improper closure of the neural tube: cell differentiation, how do they follow certain pathways. One cell or part of an embryo influencing the development of another. The lens will either not form or form in a different place if you transplant the optic vesicle to another place. How can we start to figure out what genes are important for eye lens development: find mutants with defects in eye, then map the gene and clone the gene to analyze.
