Observation on oncosphere and cysticercus of Taenia asiatica under optical microscope and scanning electron microscope

The objective of this study was to understand the morphological characters and surface ultrastructure about oncosphere and cysticercus of Taenia asiatica(T.asiatica).Eggs of T.asiatica were hatched by artificial gastric and intestinal fluids.Oncospheres were purified by density gradient centrifugation and then observed by optical microscope.And then,oncospheres were fixed by glutaraldehyde and osmium tetraoxide,dehydrated with gradient ethanol,processed in isoamyl acetate and dried by CO2 critical point method.Specimens were then sputter-coated with carbon and gold film and observed by scan electron microscope(SEM).Mice were inoculated subcutaneously with oncospheres and 55 days later,metacestodes were picked out from the mice and hatched in bile saline till the scoleces turned out.The hatched cysticerci were then observed directly under optical microscope or observed after staining by borax carmine.Cysticerci for SEM were washed by PBS for three times and processed by glutaraldehyde and osmium tetraoxide fixation,gradient ethanol dehydration,dryness,carbon spraying and gold spraying.The oncospheres were ovoid with the size of(10.7-14)μm ×(14-18.7)μm and with ridges on the unsmooth surface under SEM.The infected mice produced cysticerci,with rostellum on the scolex and with wart-like formations on the external surface of the bladder.Cauliflower-like protuberance was also found on the rostellum.The surface of the sucker was unsmooth with coral-like formations surrounding the bottom.A lot of spherical granules((1-3)μm×(3-5.5μm) were covered on the external surface of the neck.In summary,the surface of the oncosphere of T.asiatica was unsmooth and the cysticerci had obvious hookless rostellum with cauliflower-like protuberance on the top of the scoleces.