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DigeneanreproductivesystemTestes(typically)paired;vasdeferensleadstogonopore,oftenwithcirrus(intromittentorgan).SpermintroducedintogenitalporeofanotherDigenean.Insomespecies(egClonorchis,Fasciola,Notocotylus)Laurer’scanalactsasavagina.
Ovary(typicallysingle)leadsthroughoviducttoootypewhichalsoreceivesvitellineducts.Fertilizationandshellformationoccurhere.Uterusleadstogenitalpore.Eggsleavebygenitalpore.
Developmentinsnail
Cercariae:miracidiaenterssnailbypenetrationormorerarelybyingestion.Developmentproceedsthroughsomecombinationofsporocyst,daughtersporocyst,redia,daughterredia.Culminatesincercariaewhichleavesnailtoinfectnewhost.
Cercariaevaryinformdependingongroup
Cercariaedooneofthreethings:
• Penetratefinalhost(egSchistosomaspp.)
• Penetrateandencystasmetacercariainvegetation(egFasciola,Quinquiserialis)
• Penetrateandencystonsecondaryintermediatehost(e.g.Clonorchis,Echinostoma,Dicrocoelium,Paragonimus)
Schistosomamansoni
Schistosomalifecycle
Schistosomamansoniinvenousdrainageoflargeintestine.
S.Japonicuminvenousdrainageofsmallintestine.
S.Haematobiuminvenousdrainageofurinarybladder(eggspassedinurine).
Echinostoma
Fasciolahepatica
Notocotylusquinqueserialis=Quinqueserialisquinqueserialis
Dicrocoeliumdendriticum
Paragonimuswestermani
Clonorchissinensis
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