Taenia Classification:Taxonomicranksunderreview(cf.EncyclopedicReferenceofParasitology,2001,Springer-Verlag)Metazoa(Animalia)(multicellulareukaryotes,animals)Platythelminthes(flatworms)Cestoda(tapeworms)Eucestoda(segmented,hermaphroditic)Cyclophyllidea(terrestrialcycles,scolexwithsuckers)Family:TaeniidaeCyclophyllideantape-wormshaveflatribbon-likebodies,withananteriorscolex(hold-fastorganwithsuckersandsometimeshooks)andaposteriortape(strobila)madeupofsegments(proglottids).Adultwormslackagut(theyabsorbnutrients)andtheyarehermaphroditic(segmentscontainingbothmaleandfemalereproductiveorgans).Theyhaveindirectlife-cyclesinvolvingencystmentoflarvae(metacestodes)inthetissuesofintermediatehostsandtheirtransmissiontodefinitivehostsbycarnivorism.Variousspeciesareparasiticinmammals,birds,reptilesandamphibians.Adultstagesarerarelypathogenic,buttheencystedlarvalstagesmaycausespace-occupyinglesions(cysticerci)indomesticanimalsandhumans.Taeniasaginata[thisspeciescausescysticercosisincattle]Taeniasolium[thisspeciescausescysticercosisinpigsandhumans]Parasitemorphology:Thesetape-wormsformthreedevelopmentalstages:eggs,larvaeandadults.Themorphologicalcharacteristicsoftheadultsaredistinctive;alladultshavingananteriorscolex(holdfastorgan),withfourmuscularsuckers,surmountingalong(upto10m)strobila(tape)madeupofnumerous(asmanyas2,000)proglottids(segments).ThescolexofT.soliumisspheroidal,around1mmindiameterandisarmedwithtwocirclesof22-32hooks,whilethatofT.saginataiscuboidal,around2mminsectionandun-armed.Adultwormsarehermaphroditicwithsegmentscontainingbothmaleandfemalereproductiveorgans.Anteriorsegmentsareusuallyimmatureandbroaderthanlong,middlesegmentswithfullydevelopedgenitaliaaresquare,andposteriorsegmentsaregravid(filledwitheggs)andlongerthanbroad.Theeggsofbothspeciesaresimilarinmorphology;beingspherical,40-48µmindiameter,surroundedbyathickstriatedwall,andcontainingahexacanth(six-hooked)embryo(oncosphere).Thelarvalstages(metacestodes)ofT.saginataandT.soliumformdistinctivepearly-whitecys