e24.Development-of-Digestive-and-Respirat0ry-Syste(ppt文档).ppt

组织胚胎学课件组织胚胎学课件 七年制英文医学班专用七年制英文医学班专用中国医科大学中国医科大学基础医学院基础医学院组胚组胚英文教学组英文教学组Chapter 24 Development of digestive and respiratory system*digestiveandrespiratorysystemderivedfromprimitivegut/foregut/midgut/hindgut-epi.of digestive and respiratory systemderivedfromendoderm-CT and MT of digestive and respiratorysystem derived from splanchnic or visceralmesoderm1.Development of digestive system1)derivativesofpharyngealpouch-pharyngealpouch:/outpocketings of endodermal lining of theprimarypharynx(extendsfromthebuccopharyngealmembranetothetracheobronchialdiverticulum)/5pairs-derivativesofpharyngealpouch:Firstpharyngealpouch:-distalportion:widenintoasac-likestructure-middle ear cavity,the branchial membraneformtympanicmembraneoreardrum-proximal part:remain narrow to form thepharyngotympanicorEustachiantubeSecondpharyngealpouch:-distalportion:obliterated-remainingpartproliferateandformprimordiumofthepalatinetonsilThirdpharyngealpouch:-dorsal portion:differentiates into inferiorparathyroidgland-ventralpart:cellsdifferentiatesandformtwocell cords,fuse with each other behind thethoraxtogiverisetothepromordiumofthethymusFourthpharyngealpouch:-dorsal portion:forms superior parathyroidgland-ventralportion:degeneratesFifthpharyngealpouch:-gives rise to the ultimobranchial body,immigrate into thyroid and differentiate intoparafollicularcells*developmentofthyroidgland-thyroidprimordium:bythe4thweek,endodermalproliferationofthefloorofprimitivepharynx,thendescendsinfrontoftheprimitivepharynxasabilobeddiverticulum-thyroglossalduct:anarrowcanalconnectingprimitivepharynxwiththyroidprimordium,bythe6thweek,becomessolidanddisappears.-foramencaecum:-thyroglossalcystandfistula:acysticremnantofthethyroglossalduct,maybefoundatanypointalongthemigratorypathfollowedbythethyroidgland;sometimesathyroglossalcystisconnectedtotheoutsidebyafistulouscanal,calledthyroglossalfistula2)developmentofesophagusandstomachdevelopmentofesophagus-derivedfromprimitivegutextendingfromthelaryngotrachealdiverticulumtostomach-with thedescent oftheheart and lungs,itlengthensrapidly-muscular coat,formed by surroundingmesenchyme/striatedinuppertwo-thirds/smoothinlowerone-thirddevelopmentofstomach-by 4th week,appears as a fusiformdilationofforegut-greater and lesser curvatures:by the 5thweek,posteriorpartofstomachgrowfasterthantheanteriorportion-by7-8thweek,aroundthelongitudinalaxis,the stomach carries out a 90clockwiserotation,itsleftsidetofaceanterior-rotation around the transverse axis,thecaudal(pyloric)endofthestomachmoves upward and to the right;the cephalic(cardiac)endmovesdownwardandtotheleftdevelopmentofintestinea.midgutderivatives:-duodenumformation:/formed by terminal part of foregut and thecephalicpartofthemidgut/“C”-shapedventrally,rotatestotheright-midgutloop:by5thweek,midgutgrowrapidly to form a“U”-shaped loop,itsapexconnectswithyolksacbywayofthenarrowvitellineduct/cephaliclimb/caudallimb-physiologicalumbilicalherniation:during the 6th week,midgut loop growrapidly,enter the umbilical coelum-extra-embryonic coelom(in umbilicalcord)-by6-8thweek,midgutlooprotates90aroundanaxisformedbythesuperiormesentericarteryinacounterclockwisedirection,move cephalic limb to right,caudallimbleft-caecal swelling:a conical dilation ofthe caudal limb,form caecum andappendix-by10thweek,midgutloopreturntotheabdominalcavity,simultaneouslyrotates 180 in a counterclockwisedirection,move cephalic limb to left,caudallimbright-cephalic limb:develop into jejunumandmostpartofileum-caudal limb:terminal part of ileum,caecum,appendix,2/3transversecolonb.hindgutderivatives-give rise to 1/3 transverse colon,descendingcolon,sigmoid-cloaca:dilation of terminal part ofhindgut,connectwithallantois,closedbycloacalmembrane-urorectalseptum:by6-7thweek,mesenchymabetweenhindgutandallantoisproliferatesandformatransverseridge,dividedthecloacaintourogenitalsinusandanorectalcanal-urogenitalsinus:ventralportionofcloaca,developsintobladderandurethra-anorectalcanal:dorsalportionofcloaca,developsintorectumanduppersegmentofanaltube3)developmentofliverandpancreasdevelopmentofliverandgallbladder-hepatic diverticulum:by beginning of4th week,endodermal proliferation ofendoftheforegut-hepaticdiverticulumextendsintotheseptumtransversumanddividesintoalargecephalicandasmallcaudalpart-cephalicpartcellsproliferatetogiverisetohepaticcordandbileduct-cysticdiverticulum(caudalpart):developintogallbladderandcysticduct-thepairedvitellineveinsandumbilicalveinformhepaticsinusoids-at about 6th week,blood stem cellimmigrate into liver from yolk sac,hemopoiesisbegindevelopmentofpancreas-dorsalpancreaticbudandventralpancreaticbud:bytheendof4thweek,arisefromtheendodermofcaudalpartoftheforegut-dorsalpancreas,ventralpancreas:pancreaticbudscellsproliferatetogiverisetoacinusandducts-the ventral pancreas rotates to right-dorsaldirectionandfusewithdorsalpancreas-theventralpancreasformstheinferiorpartoftheheadofthepancreas;dorsalpancreasformsotherpartofpancreas-mainpancreaticduct,togetherwiththecommonbileduct,enterstheduodenumatthesiteofthemajorpapilla4)congenital malformations of the digestivetractatresiaorstenosisofdigestivetract:causedby failure of recanalization or improperrecanalization,mostly in esophagus andduodenumcongenitalumbilicalhernia:causedbyincompleteclosureofthecentralpartoftheabdominalwall,theviscerareturntotheabdomenbutherniatedagainduringthefetalperiodumbilicalfistulaandMeckeldiverticulum:-umbilicalfistula:resultsfrompersistenceofa patent vitelline duct,meconium or mucusmaybefoundattheumbilicus-vitellinesinus:resultswhenasmallportionofductremainsandopensontotheskin-vitelline cyst:results when intermediatepatentleaves-vitellineligament:vitellineductpersistasafibrouscord,willcauseintestinalobstruction-Mcekelsdiverticulum:causedbypersistenceofashorelengthofthevitellineduct,thatremainsattachedtoileum congenital aganglionic megacolon:results from the absence of ganglioncell of the parasympathetic ganglia,which cause failure of the distalsegmenttomovetheintestinalcontentsonwardimperforate anus,rectal atresia andrectalfistula:-imperforate anus:results from failureruptureofanalmembrane-rectalatresia:duetoafailureoftheanalpitto develop or deviation of the urorectalseptumindorsaldirection-rectalfistula:associatewithanimperforateanus,betweentherectumandthevaginaorurinarybladderorurethraabnormalrotationoftheintestinalloop:nonrotation or reversed rotation of themidgut atresia of the gall bladder and bileducts:resultsfromfailureofvacuolization of the epithelial cords orreopenannularpancreas:ventral pancreaticbud give rise totwobranches,which rotate theduodenum in anopposite direction,the duodenum iscompletelysurroundedbypancreatictissue2.development of respiratory system1)developmentoflarynx,tracheaandlung-laryngotrachealgroove:bythebeginof4thweek,shallowgroovefromtheventralwallofthe foregut caudal to the hypobranchialeminence-laryngotrachealdiverticulum:laryngotrachealgroovedeparatedfromforegutbytheesophagotrachealseptum-lungbud:bytheendof4thweek,laryngotracheal diverticulum forms two lateraloutpocketings.By the 5th week,the right lungbud divides into three branches-main bronchi,andtheleftintotwomainbronchi.Bytheendof2ndmonth,lobarbronchidividedintosegmentalbronchi.Bytheendof6thmonth,approximately17generationsofsubdivisionsformedandgiverisetoterminalbronchi,respiratorybronchiandalveoli.By 7th month,type II alveolar cellappears.-splanchnic mesoderm develops into the CT,cartilage,SMandvisceralpleura2)congenitalmalformations tracheal stenosis or atresia:caused byfailureofreopenorunequaldivisionoftheforegut tracheoesophageal fistula;imcompletedevelopmentordeviationoftracheoesophagealseptum,withesophagealatresiahyalinemembranedisease(respiratorydistresssyndrome):incompletedevelopmentoftypeIIalveolarcells,amembrane-like substance is formedfromtheinjuredpulmonarycells pulmonary agenesis and pulmonaryhypoplasia: