The fine structure of adult Onchocerca volvulus recovered by collagenase digestion.

Very young, middle-aged and old macrofilariae of Onchocerca volvulus were isolated alive or intact from onchocercomata using the collagenase digestion technique and studied by transmission electron microscopy. The body wall and the internal organs showed a well preserved morphology and no differences were detected compared with worms which had not been in contact with collagenase solution.