Life cycle of the beef tapeworm (Taenia saginata).

1) A person eats undercooked beef containing a cyst (resting form) of the tapeworm.
2) In the human intestine, the tapeworm uses its barbed scolex to attach to the intestinal wall. It grows by adding new body units (proglottids). Over time, it can become many meters long.
3) Each proglottid produces both eggs and sperm, and can fertilize itself or another. Proglottids that hold fertilized eggs leave the body in feces.
4) Cattle eat grass contami-nated with larva-containing proglottids.
5) The larval tapeworm matures, reproduces asexually, and forms  a cyst in its host’s muscle.