Ultracut e ultramicrotome

Adult tapeworms were immediately rinsed with a 0.9% NaCl solution. Later, they were fixed in cold (4 ºC) modified Karnovski fixative (4% paraformaldehyde and 0.25% glutaraldehyde) in a 0.1 F o r P e e r R e v i e w buffer at pH 7.4, post-fixed in cold (4 ºC) 1% osmium tetroxide with 0.9% potassium ferricyanide [K 3 Fe(CN) 6 ] in the same buffer for 1 h, rinsed in Milli-Q water (Millipore Gradient A10), dehydrated in an ethanol series and propylene oxide, embedded in Spurr's resin and polymerized at 60 ºC for 72 h.
Ultrathin sections (60-90 nm thick) were obtained with a Reichert-Jung Ultracut E ultramicrotome. Sections were placed on 200-mesh copper grids and double-stained with uranyl acetate and lead citrate.
The hexacanths of T. congolensis were reconstructed from the consecutive semithin serial sections, stained with 1% methylene blue in borax solution, by means of light microscopy, and partially from the ultrathin sections, by means of TEM.
The grids were examined in a JEOL 1010 TEM operated at 80kV, in the "Centres Científics i Tecnològics" of the University of Barcelona (CCiTUB).

The cells were fixed in 2.5% glutaraldehyde solution in phosphate buffer 0.1 M pH 7.2 (PB) for 2 hours at 4°C, washed in PB, post-fixed in 1% OsO 4 in PB for 30 minutes at 4°C, dehydrated in an ascending alcohol series, incubated twice in propylene oxide and finally infiltrated and embedded in epon/araldite resin that was polymerized at 60°C for 48 hours. Ultrathin sections (60 nm thick) were cut from samples on a Reichert-Jung Ultracut E ultramicrotome. They were mounted on 200-mesh copper grids, stained with uranyl acetate and lead citrate, and observed in a FEI Technai G2 SPIRIT transmission electron microscope at an electron accelerating voltage of 100 kV under standard operating conditions.