Material for transmission electron micron microscopy was washed in buffer. Post-fixed in a 1% solution of osmium tetroxide in 0.1 M phosphate buffer, dehydrated in an ethanol series and embedded in spurr’s epoxy resin (spur,1969). Samples were then sectioned at 130 mm using a diamond knife in a Leica UCT ultramicrotome (leical microscopy systems Ltd., Heerbrugg, Switzerland),mounted on copper sample grids and stained sequentially with a saturated solution of uranyl acetate in 50% ethanol followed by aqueous lead citrate (roland,1978). Transmission electron microscopy was carried out using a jeol jem-1200EXII transmission eletron microscope (JEOL Tokyo,Japan) operating at an accelerating voltage of 80kV.