How is the body of a tapeworm organized?
The body of tapeworm is composed of successive segments called proglottids.
Proglottids are continually produced by the neck region of the scolex, as long as the scolex is attached and alive. Mature proglottids are essentially bags of eggs, each of which is infective to the proper intermediate host. The proglottid farthest away from the scolex are the mature ones containing eggs.
Mature proglottids are released from the tapeworm's end segment and leave the host in feces or migrate as independent motile proglottids. This phenomenon serves to limit the length of the parasite and to transfer the developing embryo to the exterior in feces of the host.
Proglottids may be of three types - immature, mature and gravid. The chain of proglottids may reach a length of 15 or 20 feet. Each proglottid contains a complete set of male and female reproductive organs. Fertilisation is internal. In few species self fertilisation between two adjacent proglottids of the same worm or within the same proglottids may occur.