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1、StructureandFunctionofVertebrateandInvertebrateActiveZones12CraigC.GarnerandKangShen1DepartmentofPsychiatryandBehavioralScience,NancyPritzkerLaboratory,StanfordUniversity,PaloAlto,CA94304-5485,USA,cgarner@stanford.edu2DepartmentofBiology,StanfordUniversity,PaloAlto,CA943
2、05-5020,USA,kangshen@stanford.edu1IntroductionAsabiologist,oneisfrequentlystruckbythesynchronybetweenformandfunctionandhowitfacilitatestheabilityoforganismstoadapttodifferentenvironments.Thisconceptextendsfromthegrossanatomicalfeaturesofplants,animalsandaquaticcreaturesd
3、owntotheshapesandattributesofindividualcelltypesandtheircellularorganelles.Withinthenervoussystem,formandfunctionareessentialdriv-ingelementsincreatingthemyriadofneuronalandglialcelltypes,theircaptivatingmorphologiesandmesmerizingnetworksofaxons,dendritesandprocesses.How
4、-ever,thematchbetweenformandfunctioncanalsobeseenatthelevelofinter-cellularanatomyasoligodendrocytesandSchwanncellsensheathaxonsformingmyelinorastrocyticend-feetenvelopecapillariestocreatethebloodbrainbarrier.Forthoseinterestedininter-neuronalcommunication,nature’sbeauty
5、inmatch-ingformandfunctionisalsopresentatthetinysitesofcell–cellcontactformedbetweenneuronalcells,calledsynapses.Thesemicronsizestructuresarethekey,notonlyforencodinghigherordercognitivefunctions,butalsothesimplereflexrespon-sivenessofbothlargeandsmallanimalstoadversesti
6、muli.Surveyingthemorpho-logicalandultra-structuralfeaturesofsynapsesacrossspeciesandevenwithinasingleorganism,oneisimmediatelystruckbothbythesimilaritiesanddifferencesinthemorphologyofsynapses.Atfirst,itishardtounderstandwhysomesynapsesarelarge(hippocampalmossyfiberbouto
7、ns)andothersaresmall(excitatorypyramidalcellsynapses),orwhyothersexhibitelaborateconvolutedandinvolutedmembrane-oussubstructures(neuromuscularjunction).However,asneuroscientistsbegintodefinethefunctionalpropertiesofneuronsandtheirsynapticconnections,itbecomeseasiertoseeh
8、owonceagainsynapticform/morphologyistightlycoupledtothefunctionalpropertiesofdifferenttypesofsynapses.I