The cysticercus of taeniids is located in skeletal muscle, as shown in this photo, or other tissues. Muscle fibres are seen around the margins of this cross section. Within the clear area at the centre of the photo is the cysticercus. It is a fluid-filled bladder, into which is inverted a scolex and short strobila that will become the future adult worm. The walls of the bladder are quite thin, and you can see that the parasite within does not fill it up completely. The strobila is the large round mass of tissue in the centre of the cysticercus; the smaller circular structure just below the centre is the scolex.