zoo lecture 21 part 1

zoo lecture 21 part 1 - Week Three: November 19-21 Adult...

Info iconThis preview shows pages 1–5. Sign up to view the full content.

View Full Document Right Arrow Icon
Week Three: November 19-21 Adult derivatives - As the neural tube develops, it will make several subdivisions in a cephalic-decaudal fashion – the first differentiation occurs at the head region and the last differentiation occurs at the tail. - Rhombencephalon – hindbrain - The eye develops from regions in the diencephalon. Differentiation of the Neural Tube - Differential cell division – placodes (thickened preseumptive epidermal ectoderm tissue that forms sites of sensory innervations) - Selective cell die off – thinner regions – the roof of the neural tube is very thin and sometimes tends to collapse on itself - Flexures – cell shape changes, bends and convolutions (movements of cells) - Driven by cell adhesion molecules? The N-cadherins (neural crest cell migrations from to make the neural plate)
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Development of the eye - Drawing Xenopus - Fig 6.1 - Where an optic cup forms associated with the diencephalon, there is a formation of a lens vesicle that becomes closely associated with the optic cup. If we removed it, no such vesicle would form. If we put the optic cup if flank tissue, it would also not form the lens. This is because Pax6 is not being produced in this tissue. In some amphibians, Pax6 is produced and you can form this lens in flank tissue.
Background image of page 2
Induction of the Lends of the eye - Competence of the tissue - Pax6 protein o Sonic hedgehog – important in how the bilateral tissues are constructed. It is coming from the optic cup and interacts with the cells producing Pax6 to help form the lens vesicle - Instructive versus permissive – another tissue will not induce lens formation. This means that this type of induction is instructive . This is because the optic cup will induce the lens vesicle. No lens vesicle will be produced if the optic cup is removed. If we take tissue from any other part of the body (ex – endoderm) , it will not induce a lens vesicle even in a region that is expressing Pax6. If the endoderm does produce a lens vesicle, we know that all Pax6 competence tissue just needs a kickstart and then it knows to go ahead and form what it needs to form. But only neural ectoderm form the diencephalon will work. If we take the optic cup and place it in a flank of other species, the optic cup can produce a lens vesicle in other parts of the body. - Paracrine induction – does not require cell contact, does require a variety of growth and differentiation factors
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Normal and Abnormal Eye development - Pax6 is a common denominator for photoreceptive cels - Separation of eye field is dependent on sonic hedgehog expression in prechordal plate mesoderm
Background image of page 4
Image of page 5
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 07/22/2011 for the course BIOL 3156 taught by Professor Lynn,j during the Spring '08 term at LSU.

Page1 / 10

zoo lecture 21 part 1 - Week Three: November 19-21 Adult...

This preview shows document pages 1 - 5. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online