Bạn đang xem bản rút gọn của tài liệu. Xem và tải ngay bản đầy đủ của tài liệu tại đây (122.49 KB, 3 trang )
48
ArteryoftheFifthAorticArch
SaurabhK.Gupta,SimonD.Bamforth,RobertH.Anderson
Abstract
Mostembryologytextbooksshowsixpairsofpharyngealarcharteries,but
theexistenceofthefiftharcharteryhaslongbeencontroversial.Sixpairs
ofbilaterallysymmetricarteriesdevelopingwithinthepharyngealarches
haveyettobedemonstratedinanymammalianoravianspecies,but
collateralchannelsbetweenthedistalendsofthefourthandsixtharch
arteriesarefrequent.Wehavestudiedonlyonehumanembryoinwhichwe
foundachannelthatcouldpotentiallyqualifyasanarteryofthefiftharch.
Thepurportedchannelsnonethelessareinvokedwithincreasingfrequency
bypediatriccardiologiststoexplainvariouslesionsfoundincongenitally
malformedhearts,suchasdouble-barreledaortaandvarioussystemic-topulmonarychannelsfeedingthepulmonarycirculationinthesettingof
pulmonaryatresia.Abnormalbranchingofthebrachiocephalicarteriesis
alsofrequentlyinterpretedonthebasisofpersistenceoftheallegedartery
ofthefiftharch.Thischapterprovidesanaccountofnormaldevelopment
ofthearteriesformingwithinthepharyngealmesenchymeandextending
bilaterallytojointhedescendingaorta.Weshowthefeaturesofthesolitary
channelthatwebelieverepresentsthefiftharcharteryinahumanembryo.
Wethenprovideourowninterpretationofthevariousdescriptionswithin
theworldliterature,providingillustrationsofthosewebelievedeserve
recognitionasfiftharcharteries.Wesuggestthatmoreconvincing
alternativeexplanationscanbeadvancedtoaccountforthemajority.
Althoughtheinterpretationsdonotnecessarilychangetherapeutic
approachestothechannels,appropriatedescriptionisimportantintermsof
theirclassification.Thuswesuggestthat,ifitexists,afiftharchartery