Anti-WSP staining in transverse sections of D. medinensis and B. malayi . Wolbachia are shown as red punctate staining in the lateral hypodermal cords of B. malayi (A) but are absent from D. medinensis (B and D) as well as in tetracycline-treated B. malayi (C). Solid red arrows highlight Wolbachia within the hypodermal cords. Open black arrows indicate uteri containing developing embryos. B. malayi images are x200 magnification. D. medinensis images are x40 (B) and x100 magnification (D). Scale bars = 100 μm.