Abstract:
Four valid species of Sarcocystis have been reported from the water buffalo (Bubalus bubalis): Sarcocystis fusiformis,
Sarcocystis buffalonis, Sarcocystis levinei and Sarcocystis dubeyi. Here, we redescribe structure of S. fusiformis sarcocysts
by scanning and transmission electron microscopy (SEM, TEM). Twenty-one macroscopic sarcocysts from oesophagus
of the water buffalo in Egypt were examined by light microscopy, SEM and TEM. The sarcocyst wall was up to 9 μm
thick, depending on the section and the technique. In 5 μm paraffin-embedded sections, the sarcocyst wall was indistinct,
2–5 μm thick and appeared smooth. In 1 μm plastic-embedded sections stained with toluidine blue, the sarcocyst
wall was 2·5–5·2 μm thick and had branched villar protrusions (vp)-like branches of a dead tree. By SEM, the sarcocyst wall
had a mesh-like structure with irregularly shaped vp that were folded over the sarcocyst wall. On each vp there were
uniform papillomatous structures that were 100 nm wide. By TEM, vp were up to 6 μm long and contained
filamentous tubular structures, most of which were parallel to the long axis of the projections; granules were absent
from these tubules. By TEM, bradyzoites within the same cyst varied from 11·2 to 16·8 μm in length. By TEM,
bradyzoites had a very long (10 μm) convoluted mitochondrion, up to 12 dense granules, but only 2 rhoptries. This
redescription should help to differentiate the sarcocysts of S. fusiformis from similar sarcocysts in domestic and wild
ruminants.
