No changes in the flukes observed at 0 h of the assay. The
flukes were motile both in the control and experimental groups.
After 3 h incubation, no significant changes were also observed
and all flukes remained motile. After 6 h incubation, the control
group remained motile while reduced motility and curling were
observed in the flukes from the experimental group. However,
despite the slow movements and curling observed from the
flukes exposed to lead all flukes were still viable. The presence
of black precipitates in the medium of lead-treated flukes which
could be waste metabolic products due to stress response was
likewise observed. After 9 h incubation, flukes in the control
group were still motile. However, in the lead-treated groups,
flukes seemed immobile but were still moving when tapped with
a forceps. Thus, all flukes were still viable at 9th hour. Curling
of flukes and black precipitates were still observed in the
experimental group which were not present in the control group.
Same observations were noted after 12 h incubation. After 15 h
incubation, flukes in the control group remained motile while
flukes exposed to different concentrations of lead showed signs
of immobility. Therefore, immobile flukes were stained with 1%
methylene blue to determine the motility score of each fluke. No
significant visual differences observed between flukes with a
motility score of 1 and 0.