Echinococcus multilocularis (continued)
CHARACTERISTIC OF E. granulosus
SIZE: Up to 200 mm.
CYST WALL: Limiting membrane.
THICK OUTER: Laminated acellular layer.
THIN INNER: Nucleated germinal layer.
PROTOSCOLICES: Miniature invaginated scolices on germinal layer of cyst wall.
BROOD CAPSULES: Formed from germinal layer; contain protoscolices.
DAUGHTER CYSTS: Replica of mother cyst, formed as germinal cells penetrate
laminated layer; contain protoscolices and brood capsules
(rarely seen with this organism).
CHARACTERISTIC OF E. multilocularis
SIZE: Usually poorly defined.
CYST WALL: Unlimiting membrane.
THIN OUTERvOutgrowing processes of germinal cells.
PROTOSCOLICES: Miniature invaginated scolices; formed in fluid-filled pockets; few in
number in human infections.
BROOD CAPSULES: Absent.
DAUGHTER CYSTS: Replica of mother cyst, formed as alveolar pockets separate from
the cyst wall; numerous in number and frequency; direct metastases.
Figure 3-55. Stages of Echinococcus multilocularis. (concluded)