Tapeworms, or cestodes, are flat, ribbon-like parasites that are mostly acquired by ingestion of undercooked or raw pork, beef or fish. Depending on the species, they can range in length from a few centimeters to up to 45 feet. The adult tapeworm is divided into several sections, each with a different function.
The scolex is at the anterior portion of the tapeworm. It might be considered the head of the tapeworm. The scolex is equipped with suckers for attachment to the intestines of the animal or human host.
The crown of the scolex is called the rostellum. The rostellum can be armed (with hooklets) or unarmed (devoid of hooklets). The hooklets are also used for attachment to the host.
The strobila is a tape-like chain of progressively developing segments called proglottids. Separating the scolex from the strobila is the neck.
The majority of the tapeworm is made up of proglottids. Some species of tapeworm can have up to 3,000 proglottids with massive egg potential. They develop progressively, immature to mature to gravid from the neck. Each mature proglottid has its own male and female reproductive organs and uterine branches that are packed with ova (eggs) when mature.
The cuticle is a homogeneous, elastic covering for the tapeworm. It is continuous from one segment to another. The tapeworm absorbs food and nutrients from its host through the cuticle.
- Koneman's Color Atlas and Textbook of Diagnostic Microbiology, Elmer Koneman, M.D., 2006