Cellular analysis indicates absence of endosymbionts in Dracunculus species. Tissues from D. medinensis (A), D. lutrae (B) and D. insignis (C) were stained with propidium iodide as described  and compared to Wolbachia-harbouring Brugia malayi tissues (D). A, A’, B, D and C, lateral hypodermal cords (scale bar = 50 μm); B’, C’ and D’, embryos (scale bar = 10μm); A” and D”, microfilariae (scale bar = 50 μm). The bars at top left of the panels represent the length of half a cord. In panels A and A’, arrows point to smaller nuclei of about 4 μm, from tissue underlying the hypodermis. In panels D, D’ and D”, long arrows point to Wolbachia foci.