Dipylidium caninum, Echinococcus granulosus and Hydatigera taeniaeformis: Histochemical identification of cholinesterases

Abstract

The nervous systems of the tapeworms Dipylidium caninum, Echinococcus granulosus and Hydatigera taeniaeformis were stained by esterase techniques. The central nervous system in the scolex consists of two lateral ganglia and a pair of dorsal and ventral longitudinal nerve cords which separately join the rostellar nerve ring and are also interconnected by additional commissures. Three longitudinal nerve cords run posteriorly from each ganglion making with the dorsal and ventral nerve cords a total of 10. These are connected by many small transverse nerves throughout the strobila. The peripheral nervous system consists of small nerves from the longitudinal nerve cords supplying the musculature and tegument, a peripheral nerve net lying between the protoplasmic extensions of the tegument cells, both with many nerve endings in the tegument. Some cholinesterase inhibitors were used to characterize the enzyme: eserine completely inhibited the enzyme; BW284C51 reduced enzyme activity; and the organophosphates, Mipafox and iso-OMPA had little effect, while DFP and E600 were effective only at relatively high concentrations. It was concluded that there is an acetylcholinesterase in the three species examined, that butyrlcholinesterase was not present in E. granulosus, and that there were no nonspecific esterases.