Light micrograph of a cysticercus, an immature stage of the pork tapeworm, Taenia solium, in a biopsy specimen from a child's brain. Humans are the main primary host of this tapeworm, which infects some 4 million people worldwide. The eggs of the tapeworm develop into larvae in domestic pigs (hence the tapeworm's name) & other animals. Humans can also act as secondary hosts, as in this case; the eggs develop into cysts containing the larval stage in various tissues of the body. These cysticerci are 1 to 2 cm in diameter when fully developed. They can cause serious damage to the brain, epilepsy being a common symptom. Magnification: x8 at 35 mm size,.