Final answer:
Dipylidium caninum eggs contain several hexacanth larvae, which develop into cysticercoids inside an intermediate host before maturing into adult tapeworms in the final host.
Step-by-step explanation:
Each egg of Dipylidium caninum, commonly known as the dog tapeworm, contains several larval forms, specifically known as hexacanths, which are the six-hooked larvae. When these eggs are ingested by an intermediate host, typically fleas, the hexacanths hatch and develop into cysticercoids within the flea's body. Eventually, when a definitive host, such as a dog or cat, ingests an infected flea, the cysticercoids mature into adult tapeworms within the small intestine of the host.