Histogenesis of the rostellum of Taenia crassiceps (Zeder, 1800) (Cestoda), with special reference to hook development

Abstract

Histogenesis of the rostellum of Taenia crassiceps is described. The syncytial tegument and various cells take an active part in this differentiation. The increase in number of these cells as well as nuclei associated with the tegument, and changes in their relationship with one another, dominate the process. A specialized portion of the tegument termed the "hook organ" and its function in rostellar hook formation is considered. Rostellar hooks are produced de novo and not from fused microtriches as stated by some. When the hook organ is most active it is not separated from the underlying tissues by the subtegumental circular and longitudinal muscle layer as is the tegument of the adjacent bladder wall. When the rostellar hooks are fully differentiated the hook organ becomes an inner and outer ring of receptacles each with its own hook.