STRUCTUREOFTHEAVIANLYMPHOIDSYSTEM

STRUCTUREOFTHEAVIANLYMPHOIDSYSTEM禽类淋巴系统的结构IMREOLÁH*LONNEKEVERVELDE†作者万建美译*DepartmentofHumanMorphologyandDevelopmentalBiology,SemmelweisUniversity,TuzoltoStr.58,Budapest1094,Hungary†DepartmentofInfectiousDiseasesandImmunology,FacultyVeterinaryMedicine,UtrechtUniversity,POBox80.165,3508TDUtrecht,TheNetherlandsINTRODUCTION引言THEGCOFPERIPHERALLYMPHOIDORGANS外周淋巴器官的生发中心（GC）THYMUS胸腺BURSAOFFABRICIUS法氏囊SPLEEN脾脏GUT-ASSOCIATEDLYMPHOIDTISSUES肠道伴随（相关）淋巴系组织（GALT）HARDERIANANDCONJUNCTIVAL-ASSOCIATEDLYMPHOIDTISSUES哈德氏腺和结膜伴随（相关）淋巴组织（CALT）MURALLYMPHNODE附壁淋巴结ECTOPICLYMPHOIDTISSUEANDTHEPINEALGLAND异位淋巴样组织和松果腺BONEMARROW骨髓BLOOD血液REFERENCES参考文献INTRODUCTION引言Understandingthephysiologyandimmunologyofthelymphoidsystemishandicapedwithoutknowledgeofitsbasicstructure.Lymphomyeloidtissuesdevelopfromepithelial(bursaofFabriciusandthymus)ormesenchymal(spleen,lymphnodesandbonemarrow)anlageswhicharecolonizedbyblood-bornehaematopoieticcells.Inthecaseofcentrallymphoidorgans,haematopoieticstemcellsenterthebursalorthymicanlagesanddeveloptobecomeimmunologicallycompetentBandTcells,respectively.Hence,BandTcellsareofextrinsicorigin,asproposedbyMooreandOwen(1965,1967)anddescribedinmoredetailinChapter3.缺少淋巴系统结构方面的知识将阻碍我们对淋巴系统生理学和免疫学的理解。淋巴髓质组织（lymphmyeloidtissues）由上皮（法氏囊和胸腺）原基或间充质（脾脏、淋巴结和骨髓）原基发展而来，而上皮（法氏囊和胸腺）原基或间充质（脾脏、淋巴结和骨髓）原基中定殖着血源性造血细胞。在中枢淋巴器官中，造血干细胞进入法氏囊原基或胸腺原基，并分别发育成为免疫活性的B淋巴细胞和T淋巴细胞。因此，正如Morre和Owen(1965,1967)提出的那样，B淋巴细胞和T淋巴细胞是非固有起源的，详细的讲述见第3章。Immunologicallymaturecellsenterthecirculationandcolonizetheperipherallymphoidorgans:spleen,lymphnodeandgut-,bronchus-andskin-associatedlymphoidtissues.Thisperipheralizationprocesscanbeexperimentallymanipulatedbysurgicalorchemicalinterventions.Thehomingofthelymphocytesoccursthroughhighendothelialvenules(HEV，高内皮小静脉),whicharelocatedintheT-dependentzonesofperipherallymphoidorgans.IntheseorgansBandTcellsoccupydifferentcompartments,referredtoasB-andT-dependentzones,respectively.IntheavianspleentheT-dependentzone–calledperi-arteriolarlymphaticsheath(PALS)–surroundsthespleniccentralartery,whereasinotherlymphoidorgansthisisnotaswelldefined,andtheinterfollicularregionisregardedastheT-dependentarea.Bcellcompartmentsarethegerminalcentres(GC).InadditiontotheGCtheperi-ellipsoidalwhitepulp(PWP)ofthespleenisalsoaB-dependentregion,likethemarginalzoneofthemammalianspleen.Possibly,thisBcellpopulationinthePWPisresponsibleforproductionofantibodiesagainstbacterialcapsularantigens(pneumococcusantigen).Splenectomyofthepigeonabrogatestheantibodyresponseandthebirdsdiesoonafterpneumococcusinfection.成熟的免疫细胞进入血液循环并定殖于外周淋巴器官：脾脏、淋巴结及肠道、支气管和皮肤伴随淋巴组织。这一外周化的过程可通过手术或化学干涉进行实验性的操纵。淋巴细胞归巢的发生是通过位于外周淋巴器官胸腺依赖区（T-dependentzones）的高内皮小静脉（Highendothelialvenules,HEV）而完成的。在这些淋巴器官中，B淋巴细胞和T淋巴细胞占据着不同的区室（来源于少数几个奠基细胞的细胞群所占据身体或器官上的一定区域称为区室。属于一个分区室的细胞决不会越界同其他区室细胞混合，不同区室之间有严格的界线。），分别称为非胸腺依赖区和胸腺依赖区(B-andT-dependentzones)。在禽类的脾脏中，被称为动脉周围淋巴鞘（periarteriolarlymphaticsheath,PALS）的胸腺依赖区（T-dependentzones）包围着脾中央动脉。然而在其它淋巴器官中，胸腺依赖区并没有很好的界定，通常认为滤泡间细胞区为这些淋巴器官的胸腺依赖区。生发中心（germinalcentres,GC）是非胸腺依赖区（B-dependentzones）。除GC之外，如同哺乳动物脾脏边缘区，禽类脾脏白髓椭球周围区（peri-ellipsoidalwhitepulp,PWP）也是非胸腺依赖区。PWP中的B细胞群可能负责产生抗细菌荚膜抗原（capsularantigens,又称为K抗原）（肺炎球菌抗原）的抗体。切除脾脏的鸽子抗体应答消失，并在肺炎球菌感染后很快死亡。Thesplenicanlagedevelopsfromthedorsalmesogastrium,ventraltothenotochordanditsablationatthelowerthoracallevelabrogatessplenicdevelopment,suggestinganotochordalinductiveeffect.Haematopoieticcolonizationofthesplenicanlagebeginsabout6.5daysofincubation,contemporaneouswiththatofthethymus.Itisalsoworthmentioningthatinthespleennotonlythecellsofthehaematopoieticcompartmentbutalsootherresidentcells,liketheellipsoid-associatedcells(phagocytic)andsupportingcellsoftheellipsoid(capableofcollagenproduction)areofblood-borneorigin(Nagyetal.,2005).脾脏原基由胃背系膜腹侧至脊索部分发育而来，将该部分于胸椎远端（lowerthoracallevel）切除后脾的发育即停止，表明脊索对脾的发育有诱导效应。脾脏原基和胸腺原基造血细胞集群都开始于孵育后6.5天。值得说明的是，在脾脏中，不仅造血区室的细胞，而且其它生活细胞都是血源性的(Nagyetal.,2005)，如椭球体伴随细胞（巨噬细胞）和椭球体支持细胞（能产生胶原）。Severalperipheral,orsecondary,lymphoidtissuescanbedistinguishedinthechicken,mostnotablythespleenandmucosa-associatedtissuessuchastheeye-associatedlymphoidtissue(Harderianglandandintheconjunctivaofthelowereyelid),nasal-,bronchus-,genital-andgut-associatedlymphoidtissues(oesophagealtonsils,pylorictonsils,Peyer’spatches(PP),caecaltonsils(CT)andMeckel’sdiverticulum)andtheskin-andpineal-associatedlymphoidtissues.鸡的许多外周淋巴组织或次级淋巴组织是能够被辨识的，最显著的有脾脏和粘膜伴随组织（如眼伴随淋巴组织（哈德氏腺和下眼睑结膜中组织）），鼻、支气管、生殖和肠伴随淋巴组织（食管扁桃体、幽门扁桃体、派尔氏斑（Peyer’spatches,PP）、盲肠扁桃体（caecaltonsils,CT）和Meckel’s憩室）及皮肤和松果腺伴随淋巴组织。Secondarylymphoidorgans,unlikethethymusandbursa,arenotsitesforantigen-independentdifferentiationandlymphocyteproliferation.Mostorganizedlymphoidtissuesbegintodevelopindependentlyofantigenstimulation,sincetheyarefoundinpredilectedsitesbeforehatching.However,furthermaturationofthelymphoidtissuesisantigendriven,ascanbedemonstratedusinggerm-freechickens(Hedgeetal.,1982).与胸腺和法氏囊不同，次级淋巴器官不是抗原非依赖性分化和淋巴细胞增殖的场所。大多数有机体的淋巴组织在没有抗原刺激下开始发育，因而在胚胎的好发部位（predilectedsitesorsitesofpredilection）可找到这些淋巴组织。然而，淋巴细胞的进一步成熟则是由抗原驱动的，这一点能用无菌雏鸡进行实验而证明（Hedge等，1982）。Lym