L15 - ear development Flashcards
what is the inner ear formed from and what does it form
otic placode
cockela/sccule and semicircular canals
what is the middle ear formed from and what does it form
formed from the 1st pharngeal puch and the ossciles from the mesenchyme of the 1st PA and 2 PA
what is the external ear formed from
pa1 and pa2 and cleft imbetween
what is th mechnaics of hearing
vibr in ear drum tansmitted by small skeletal elements of ossicles to produce waves in inner ear fluids which stim the mechano rec of cochlea
where does the otic placodee form
adjacent to the presumptive neural crest regio anf epibranchial placodes
what stucutures does the ncc contribute to in the ear
incus and malleus in inner ear from PA1
stapes PA2
what does the invaginating external canal create
the external auditory meatus (EAM)
what is the eam
the primoridum of the ear drum
what envelops the middle ear ossicle
eustachian tube
what does the outer ear devleop from
6 auricular hillocks on PA1 and PA2
what does the middle ear consist of
ossicles
tympanic mbn
eustachian tube
what special about the middle ear
composite organ devleoped from all three germ layers
ecto of cleft
endo of bouch
arch mesenchym e
where do ossicles develop from
the arch mesenchyme
what patterns pa1 for malleus and incus devlopment
fgf8 required for ncc prolif and migration = arch mesenchyme and a survival factor
ko - loss of middle ear
what ispatterns pa2 and stapes and tympanic ring development
hoxa2 imp o - dup of pa1 strucutres
dlx1/2
prx1/gsc imp in tympanic ring
what is the pattern code for the strucutres of the middle ear
Dlx1/2 Dlx1/2/5/6
no hox INCUS MALLEUS
hoxa2 STAPES NONE
what th eptype of a dlx5/6 null
dup incus and modified stapes
what is the ptype of a hoxa2 null
dup of pa1 structures
what strucutre in the middle ear is reciprocal signalling between M and Epi important for and descirbe
tympanic ring
epi secrete growth factors
induce M to expr TF inc PRX1 nd GSC (both nec for tr dev)
what the role of the tympanic ring in devleop
induce signals to cause invag of EAM
what tf does EAM induce the mesenchyme to expr
sox9
direct manubrium dev
where do the singals arise that specify the otic field (inv in inner ear dev)
mesenectoderm and neuroectoderm
inc fgf3/fgf19 and wnt8c
what occurs to neuroblasts when delaminate
form the statoacoustic ganglion
what tf and signal expr before otic placode visible
pax2/sox3/bmp7/notch
