H. nana and H. diminuta, by SEM. He found that thescolex, suckers, rostellum and strobilia are all covered with
dense populations of microtriches which are all of the
same size and shape except on the scolex and suckers
which are slightly more slender than those on the
strobilia. Presently study the microtriches appeared of
uniform shape and length along the strobilar surface and
were never seen to be branched.Moreover, Abouzakham
et al. [21] studied the cytological structure of tegument of
H. nana by SEM. They found that the surface of H. nana
is covered with dense populations of microtriches occur
on scolex proper, suckers and strobilia; with an average
density of 20/Fm2. On the other hand, Jha and Smyth [22]
reported polymorphic microtriches on the rostellum of
Echinococcus granulosus. In the present study neither H.
nana nor in H. diminuta this polymorphism was
observed. Andersen [23], using SEM compared the
surface structure of adults and larvae of three species of
Diphyllobothrium and reported the presence of regional
difference in microtiches appearance in the larva, but not
in the adult cestodes. Also, polymorphism was observed
in Diphyllobothrium.