Comparative histology of the scolex and neck region of Glaridacris laruei (Lamont, 1921) Hunter, 1927 and Glaridacris catostomi Cooper, 1920 (Cestoidea: Caryophyllidea)

Abstract

The histology of the scolex and neck region was examined in adults of the caryophyllidean tapeworms Glaridacris laruei and Glaridacris catostomi, parasites of the white sucker, Catostomus commersoni (Lacépède). Several distinct cell types were identified in the parenchyma including tegumental cells, flame cells, longitudinal muscle cells (myoblasts), transverse and dorsoventral muscle cells, parenchyma cells, epithelioid cells, and cells associated with the calcareous corpuscles. The proliferative zone of germinative cells reported for strobilate tapeworms was not found in these species. Faserzellen, or neck cells, which consisted of a deeply staining mass of cells, were found in the medullary parenchyma of the neck. Histochemical tests revealed that the cytoplasm of the Faserzellen was rich in RNA and protein, but alkaline and acid phosphatase activity were not detected. The arrangement of musculature in the scolex was examined; muscles associated with the attachment organs of G. laruei appear more developed compared with those of G. catostomi. Measurements of the various cells and their characteristic staining properties are presented in tabular form.