10-Neuraltion and Patterning
• Stuff going through dorsal li[pà dorsal mesoderm • Anterior and posterior neural are different • All kinds of singalling events • All cocuring in a gradient • RAà renpic acid gradient from anterior to posterior • Gradient tells noggin where it is, allows it to make the right structure • Dorsal side makes dorsal mesoderm • 3d of mesoderm, but only dorsal emsoderm signals neural • In frog all dorsal mesoderm is there before neuralations starts; in frog neuraltation doesn’t start until gastrulation finsihes
1
• Take ectoderme befre its induced, if transplant it will form epidermis • Cells in dorsal lip. First part that go through dorsal lip is the mst anterior. Take early dorsal lip, will form another axisà mainly anterior • If take late dorsal lipà get another posterior axis • Take late dorsal lip ectodermà will form neural (has the proper stuff that induces bmp)?
2
• No need to memorize anything here • Bmp makes etoderm epidermis • On the flip side, if inhibit bmpà will form neural tube and brain and associated structures • In between the twoà get neural crest (after mid term stuff)
3
• Dorsal mesoderm is specialà forms the notochord. Notochord signals to form neural tissues • Dorsal side of embyo looks different because eof this • Dorsal mesoderm leads to primary neuratlation pf 98% • Three steps plate formation, groove formation, tube formation • First fromation of plate: • Dorsal mesoderm broad to start • Gastrulation causes dorsal emsoderm to separate and form a tube (convergence extension). At same time secreding noggin, and inibihitng bmps • Ectoderm changes shape, and mesoderm is starting to segment • First thing is nortal chord; everything makes dorsal comes from nortochords • If ur abover nortochord, get a lot of singals and become neural plate. If far away stay epidermis • Inbetween ur special, form the neural crest • Neuraltaion occurs in 3 steps: formation of neural plate, froamtion of
4
• Have plate region off thicker cells • After fromation of plate get the groove (requrires bending) • Nortochord singals using sonic hedghog; causes cells above to bend and form a groove • Calls mhp cels • Actin mypsin allows for apically constiction that’s neeed • In chickà posterior marginal zone; as thin run from through node from ant to post; have dorsal mesoderm that wll from neral plate • Epdidermis closes causing dlhpà hing e pints • Formed neural plate; bmp is inhibited • Secind step is formation of the goup • Occurs due to sonic hdghg singnalling • Sonuc hdghhg causes cells to apically contrict; fomr s a medial hingepoint • Hingepoint froms groove
5
• Eventually get closing of epidermis on top • Have dorsal mesoderm; signal to overlying ectoderm • Bmp is inhbitedà allows formation of enural plate • Nortochord signals with sonci to get plate cells to form hinge piint • Dorsal lateral hinge points close and bring top parts of tube to close
6
• In frog, have neural plate forming, then neural groove that forms in middle • Folds and zips up the tub • In frog, neural tube closes at middle and zips up towards posterior and anterior • Not simultaneos • Neural crest cells begin to migrate as soon as tibe closes • In mammals cranial neural cells migrate before closureà occurs anterior • Anterior neural differentiation occurs before closure in mmamals
7
• Have pmz • Primitive streak goes from post to ant • Hanson node goes from ant to post, leaves mesoderm • Mesoderm initially is one layer • But dorsla nesoderm segments to form notochord • Forsst thing dorsal mesoderm does is inhibt bmp and form neural plate (above dorsal mesoderm) • Neural plate will respond to sonic hedgehog and from a groove • Ectoderm closes over top forming tube • In chick tube goes from anterior to posteriopr (follows hansons node migration of mesdoerm) • In chicks gas and neuro occur simultanesly
8
• When neural tube closes, get a straw • Opening of both ends are called neuralpores (anterior and posterior) • When neural tube closes already have started to form structures (bulgesà spcially at anterior) spina bifidaà don’t close pos • Anencephalyà cant close ant • Son hedghg is needed to close among others • Also need chlosterol when forming neural tissue • Also need pholic acid
9
• Differentiation of neural tube requires differnetiation • Regions of the brains are formed early during deveopemntà swells due to fluid pressure • Folds and size of brain is dependent on fluid pressure • Cans see the fluid pressure • If inject die in chick embryyo cavity, in early embryo there is inclusopn. Usually spinal chord is open, but in this stage is closed. Allows for fluid pressure build up in anterior, allwoing it ot swell. If anterior end doesn’t close, cant swell. Once get approriate swell, inclusion is released, and spinal chord becomes open system
10
• Neural plate I sneural plate because bmp s inhibited • Intisall have ecto that is held togethter by cell adhesion molecules (especially homophillic caherins) • Dorsa mesoderm signals to from neural plate • When plate is fromed, cells change shape and expression of cadherin • Cells basically above=r nortochord are expressing n cadherin • Calles farther away are expressing e caderin • If alter cadherin expression, cause them toe xpress e instead of nà folding and no seperation
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• Formed neural tube from brain to ass • Patterned anterio and posterior • Have to pattern dorsal ventral axis of tube • Have bmp siting in epidermis • Bmp dorsalin and activinà secrete from epidermisà form roof plate • Snc hdhg from nortochors form foot plate • Memorize motor neuronsà differentiate close to the floor plate • Snc hghg is a pmorhogen • Nortochord is responible for postining moto neurons • Can transplate another nortochord and put it near roof plateà signals hghg, and from cells that lok like floor plate and get motor neurons
12
1
• Take ectoderme befre its induced, if transplant it will form epidermis • Cells in dorsal lip. First part that go through dorsal lip is the mst anterior. Take early dorsal lip, will form another axisà mainly anterior • If take late dorsal lipà get another posterior axis • Take late dorsal lip ectodermà will form neural (has the proper stuff that induces bmp)?
2
• No need to memorize anything here • Bmp makes etoderm epidermis • On the flip side, if inhibit bmpà will form neural tube and brain and associated structures • In between the twoà get neural crest (after mid term stuff)
3
• Dorsal mesoderm is specialà forms the notochord. Notochord signals to form neural tissues • Dorsal side of embyo looks different because eof this • Dorsal mesoderm leads to primary neuratlation pf 98% • Three steps plate formation, groove formation, tube formation • First fromation of plate: • Dorsal mesoderm broad to start • Gastrulation causes dorsal emsoderm to separate and form a tube (convergence extension). At same time secreding noggin, and inibihitng bmps • Ectoderm changes shape, and mesoderm is starting to segment • First thing is nortal chord; everything makes dorsal comes from nortochords • If ur abover nortochord, get a lot of singals and become neural plate. If far away stay epidermis • Inbetween ur special, form the neural crest • Neuraltaion occurs in 3 steps: formation of neural plate, froamtion of
4
• Have plate region off thicker cells • After fromation of plate get the groove (requrires bending) • Nortochord singals using sonic hedghog; causes cells above to bend and form a groove • Calls mhp cels • Actin mypsin allows for apically constiction that’s neeed • In chickà posterior marginal zone; as thin run from through node from ant to post; have dorsal mesoderm that wll from neral plate • Epdidermis closes causing dlhpà hing e pints • Formed neural plate; bmp is inhibited • Secind step is formation of the goup • Occurs due to sonic hdghg singnalling • Sonuc hdghhg causes cells to apically contrict; fomr s a medial hingepoint • Hingepoint froms groove
5
• Eventually get closing of epidermis on top • Have dorsal mesoderm; signal to overlying ectoderm • Bmp is inhbitedà allows formation of enural plate • Nortochord signals with sonci to get plate cells to form hinge piint • Dorsal lateral hinge points close and bring top parts of tube to close
6
• In frog, have neural plate forming, then neural groove that forms in middle • Folds and zips up the tub • In frog, neural tube closes at middle and zips up towards posterior and anterior • Not simultaneos • Neural crest cells begin to migrate as soon as tibe closes • In mammals cranial neural cells migrate before closureà occurs anterior • Anterior neural differentiation occurs before closure in mmamals
7
• Have pmz • Primitive streak goes from post to ant • Hanson node goes from ant to post, leaves mesoderm • Mesoderm initially is one layer • But dorsla nesoderm segments to form notochord • Forsst thing dorsal mesoderm does is inhibt bmp and form neural plate (above dorsal mesoderm) • Neural plate will respond to sonic hedgehog and from a groove • Ectoderm closes over top forming tube • In chick tube goes from anterior to posteriopr (follows hansons node migration of mesdoerm) • In chicks gas and neuro occur simultanesly
8
• When neural tube closes, get a straw • Opening of both ends are called neuralpores (anterior and posterior) • When neural tube closes already have started to form structures (bulgesà spcially at anterior) spina bifidaà don’t close pos • Anencephalyà cant close ant • Son hedghg is needed to close among others • Also need chlosterol when forming neural tissue • Also need pholic acid
9
• Differentiation of neural tube requires differnetiation • Regions of the brains are formed early during deveopemntà swells due to fluid pressure • Folds and size of brain is dependent on fluid pressure • Cans see the fluid pressure • If inject die in chick embryyo cavity, in early embryo there is inclusopn. Usually spinal chord is open, but in this stage is closed. Allows for fluid pressure build up in anterior, allwoing it ot swell. If anterior end doesn’t close, cant swell. Once get approriate swell, inclusion is released, and spinal chord becomes open system
10
• Neural plate I sneural plate because bmp s inhibited • Intisall have ecto that is held togethter by cell adhesion molecules (especially homophillic caherins) • Dorsa mesoderm signals to from neural plate • When plate is fromed, cells change shape and expression of cadherin • Cells basically above=r nortochord are expressing n cadherin • Calles farther away are expressing e caderin • If alter cadherin expression, cause them toe xpress e instead of nà folding and no seperation
11
• Formed neural tube from brain to ass • Patterned anterio and posterior • Have to pattern dorsal ventral axis of tube • Have bmp siting in epidermis • Bmp dorsalin and activinà secrete from epidermisà form roof plate • Snc hdhg from nortochors form foot plate • Memorize motor neuronsà differentiate close to the floor plate • Snc hghg is a pmorhogen • Nortochord is responible for postining moto neurons • Can transplate another nortochord and put it near roof plateà signals hghg, and from cells that lok like floor plate and get motor neurons
12
