Cestodes

What is the basic anatomy of the cestode?

• Scolex with hooks and suckers

• Strobila (body) made of proglottids

• Surface is covered with a tegument that nutrients are absorbed across

What is the basic cestode lifecycle?

1. Adult cestodes in the definite host undergo sexual reproduction and produce proglottids, which contain eggs

2. Gravid proglottids fall off the strobila and are passed in the faeces

3. Eggs are swallowed by an intermediate host, within which they hatch into larvae called metacestodes

4. The intermediate host is eaten by the definite host, and the metacestodes mature.

What are the types of metacestode?

• Cysticerus

• Cysticercoid

• Strobilocercus

• Coenurus

• Hydatid cyst

• Alveolar cyst

What is a cysticercus?

A fluid filled bladder containing a single inverted scolex

What is a cysticercoid?

A single scolex that is not inverted, and is surrounded by very little fluid. Found in invertebrates only.

What is a strobilocercus?

The scoles has a chain of segments which connect to a small fluid filled cyst. Only Taenia taeniaformis form this.

What is a coenurus?

A fluid filled bladder containing many scolices.

What is a hydatid cyst?

A fluid filled bladder containing brood capsules which contain thousands of inverted scolices that bud endogenously

What is an alveolar cyst?

Like a hydatid cyst, but it buds both exogenously and endogenously to form a collection of many cysts.