The origin of the stapes and relationship to the otic capsule and oval window.
BACKGROUND
The stapes, an ossicle found within the middle ear, is involved in transmitting sound waves to the inner ear by means of the oval window. There are several developmental problems associated with this ossicle and the oval window, which cause hearing loss. The developmental origin of these tissues has not been fully elucidated.


RESULTS
Using transgenic reporter mice, we have shown that the stapes is of dual origin with the stapedial footplate being composed of cells of both neural crest and mesodermal origin. Wnt1cre/Dicer mice fail to develop neural crest-derived cartilages, therefore, have no middle ear ossicles. We have shown in these mice the mesodermal stapedial footplate fails to form and the oval window is induced but underdeveloped.


CONCLUSIONS
If the neural crest part of the stapes fails to form the mesodermal part does not develop, indicating that the two parts are interdependent. The stapes develops tightly associated with the otic capsule, however, it is not essential for the positioning of the oval window, suggesting that other tissues, perhaps within the inner ear are needed for oval window placement.
Department of Craniofacial Development and Stem Cell Biology, Kings College London, Guy's Tower, Guy's Hospital, London Bridge, London, UK.
Hannah
H
Thompson
Atsushi
A
Ohazama
Paul T
PT
Sharpe
Abigail S
AS
Tucker
D000818:Animals; D053487:DEAD-box RNA Helicases / Q000235:genetics / Q000378:metabolism; D004423:Ear / Q000033:anatomy & histology / Q000196:embryology* / Q000502:physiology; D004429:Ear Ossicles / Q000196:embryology / Q000378:metabolism; D004622:Embryo, Mammalian; D005260:Female; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D008954:Models, Biological; D009432:Neural Crest / Q000196:embryology / Q000378:metabolism; D010046:Oval Window, Ear / Q000166:cytology / Q000196:embryology* / Q000378:metabolism; D011247:Pregnancy; D043244:Ribonuclease III / Q000235:genetics / Q000378:metabolism; D013199:Stapes / Q000033:anatomy & histology / Q000166:cytology / Q000196:embryology* / Q000378:metabolism; D051155:Wnt1 Protein / Q000235:genetics / Q000378:metabolism
D051155:Wnt1 Protein; C495246:Wnt1 protein, mouse; C509781:Dicer1 protein, mouse; D043244:Ribonuclease III; D053487:DEAD-box RNA Helicases