An improved method of examining adult Onchocerca volvulus worms

Adult Onchocerca volvulus worms were extracted from alcohol-fixed nodules by collagenese digestion. The worms were stained in Mayer's haematoxylin and brought up into glycerol. In this viscous fluid the stained and cleared worms could be unravelled in sequential lengths of 4-6 cm and mounted in glycerol on slides for longitudinal examination of their structure. The worm lengths were then cut into small pieces, 0.5 cm long, which were implanted sequentially into slits in a brick-shaped block of formalin-fixed calf's brain (white matter) also in glycerol. The brain blocks were then processed in paraffin wax and cut as 6 microns histological sections, enabling transverse sections of the worm, stained as required, to be examined in sequential order.