Cysticercoid

Cysticercoid is a larval stage of certain tapeworms, often found in insects. This stage follows the oncosphere and precedes the adult stage in the life cycle of some tapeworms. The cysticercoid consists of an invaginated scolex enclosed in a fluid-filled bladder.

Life Cycle

The life cycle of a tapeworm that includes a cysticercoid stage typically involves an intermediate host, such as an insect, and a definitive host, such as a human or other mammal. The tapeworm eggs are ingested by the intermediate host, where they hatch into oncospheres. The oncospheres penetrate the gut wall and develop into cysticercoids. When the definitive host consumes the intermediate host, the cysticercoids are released, attach to the gut wall, and develop into adult tapeworms.

Morphology

The cysticercoid is small and has a thick, resistant outer wall that protects it from the host's digestive enzymes. Inside the cysticercoid is a fluid-filled bladder that contains the invaginated scolex, or head, of the tapeworm. The scolex has hooks and suckers that it uses to attach to the host's gut wall.

Clinical Significance

In humans, cysticercoids can cause a disease called cysticercosis, which is characterized by the formation of cysts in tissues such as the brain, muscles, and eyes. Symptoms can include seizures, muscle weakness, and vision problems. Treatment typically involves antiparasitic drugs and, in some cases, surgery.

See Also

• Cysticercosis
• Tapeworm
• Oncosphere