L15 - ear development

Question 1

what is the inner ear formed from and what does it form

Answer 1

otic placode

cockela/sccule and semicircular canals

Question 2

what is the middle ear formed from and what does it form

Answer 2

formed from the 1st pharngeal puch and the ossciles from the mesenchyme of the 1st PA and 2 PA

Question 3

what is the external ear formed from

Answer 3

pa1 and pa2 and cleft imbetween

Question 4

what is th mechnaics of hearing

Answer 4

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

Question 5

where does the otic placodee form

Answer 5

adjacent to the presumptive neural crest regio anf epibranchial placodes

Question 6

what stucutures does the ncc contribute to in the ear

Answer 6

incus and malleus in inner ear from PA1

stapes PA2

Question 7

what does the invaginating external canal create

Answer 7

the external auditory meatus (EAM)

Question 8

what is the eam

Answer 8

the primoridum of the ear drum

Question 9

what envelops the middle ear ossicle

Answer 9

eustachian tube

Question 10

what does the outer ear devleop from

Answer 10

6 auricular hillocks on PA1 and PA2

Question 11

what does the middle ear consist of

Answer 11

ossicles
tympanic mbn
eustachian tube

Question 12

what special about the middle ear

Answer 12

composite organ devleoped from all three germ layers
ecto of cleft
endo of bouch
arch mesenchym e

Question 13

where do ossicles develop from

Answer 13

the arch mesenchyme

Question 14

what patterns pa1 for malleus and incus devlopment

Answer 14

fgf8 required for ncc prolif and migration = arch mesenchyme and a survival factor
ko - loss of middle ear

Question 15

what ispatterns pa2 and stapes and tympanic ring development

Answer 15

hoxa2 imp o - dup of pa1 strucutres
dlx1/2
prx1/gsc imp in tympanic ring

Question 16

what is the pattern code for the strucutres of the middle ear

Answer 16

Dlx1/2 Dlx1/2/5/6
no hox INCUS MALLEUS
hoxa2 STAPES NONE

Question 17

what th eptype of a dlx5/6 null

Answer 17

dup incus and modified stapes

Question 18

what is the ptype of a hoxa2 null

Answer 18

dup of pa1 structures

Question 19

what strucutre in the middle ear is reciprocal signalling between M and Epi important for and descirbe

Answer 19

tympanic ring
epi secrete growth factors
induce M to expr TF inc PRX1 nd GSC (both nec for tr dev)

Question 20

what the role of the tympanic ring in devleop

Answer 20

induce signals to cause invag of EAM

Question 21

what tf does EAM induce the mesenchyme to expr

Answer 21

sox9

direct manubrium dev

Question 22

where do the singals arise that specify the otic field (inv in inner ear dev)

Answer 22

mesenectoderm and neuroectoderm

inc fgf3/fgf19 and wnt8c

Question 23

what occurs to neuroblasts when delaminate

Answer 23

form the statoacoustic ganglion

Question 24

what tf and signal expr before otic placode visible

Answer 24

pax2/sox3/bmp7/notch

Question 25

what singals define the organ of corti

Answer 25

fgfr1 and fgfr3