Transmission electron micrographs of Brugia malayi female worms. Panel A and C are sections of untreated female worm. Panel A shows numerous Wolbachia (arrows) in the hypodermis. Panel C shows, intact embryos in the uterus. Panel B and D are sections from doxycycline treated worms. The hypodermis is free of Wolbachia (Panel B) and only degenerate embryos were present in the uterus of treated worms (Panel D). U, uterus; C, cuticle; UW, uterine wall; MF, microfilaria; mtr, mitochondria. Scale bar = 1 μm.