Echinococcus adult worms develop from protoscolices .
Are typically 6 mm or less in length and have a scolex , neck and typically three proglottids , one of which is immature , another of which is mature and the third of which is gravid ( or containing eggs ) .
Echinococcus adult worms develop from protoscolices and are typically 6 mm or less in length and have a scolex , neck and typically three proglottids , one of which is immature , another of which is mature and the third of which is gravid ( or containing eggs ) .