Ultrastructure of hydatid cyst.

Material from a surgically excised hydatid cyst of the liver was examined with an electron microscope. The integument of the parasite was studied in particular detail and has been defined as the tissue enclosed by the external cytoplasmic membrane of the distal cytoplasm and the basement membrane. The ultrastructural features of the different parts of the integument, ie, distal cytoplasm, lucent zone, fibrous zone, muscular layer, and the basement membrane are described. The germinal membrane covering the protoscolices had no anatomic connections with the distal cytoplasm except at the point of attachment of the protoscolex to the brood capsule. The biogenesis of the mitochondria has been traced from infoldings of the cytoplasmic membrane to calcified dense bodies.