Ultrastructure of vitellogenesis in cestode (Moniezia expansa) (Cestoda: Cyclophyllidea)

摘要

Transmission electron microscopic observations have been made on vitellogenesis in the cestode, Moniezia expansa. Four continuous developmental stages were evident: (1) an immature gonial stage prior to differentiation; (2) an early stage of differentiation; (3) an advanced stage of differentiation; and (4) the mature vitellocyte. Mature vitelline follicles consist of cells in various stages of development, distributed irregularly. Maturation of the vitellocyte is completed before the cell leaves the follicle. The process of maturation is characterized by: (1) a gradual increase in cytoplasmucleus ratio and cell volume; (2) the presence of large numbers of mitochondria; (3) the appearance of granular endoplasmic reticulum and associated Golgi apparatus; (4) the production at the Golgi of small electron dense vitelline vesicles that fuse and eventually amalgamate into one large vitelline vesicle, filling most of the cell volume. ［Acta Zoologica Sinica 49(2):256-261,2003］.