English: Under a very low magnification of only 8X; this photomicrograph revealed some of the ultrastructural morphology exhibited by three Taenia solium proglottids. Proglottids of Taenia spp. Gravid proglottids are longer than wide and the two species, T. solium and T. saginata, differ in the number of primary lateral uterine branches: T. solium contains 7-13 lateral branches and T. saginata 12-30 lateral branches. Adults of Taenia spp. can reach a length of 2-8 meters, but the hooked scolex, located at the head region, is only 1-2 millimeters in diameter. Taeniasis is the infection of humans with the adult tapeworm of Taenia saginata or Taenia solium. Humans are the only definitive hosts for these two tapeworm species.