THE ULTRASTRUCTURE OF THE BRAIN OF ADULT LIVER FLUKE, Opisthorchis viverrini

The organization of the nervous system has been documented for various helminth parasites. However, the ultrastructure of the brain of the carcinogenic liver uke, Opisthorchis viverrini has not been described. This study therefore clarified the fine structure of the cerebral ganglia (brain) of this uke using transmission electron microscopy. The cerebral ganglia of O. viverrini are composed of ganglion cell bodies and the bilateral lobe of neuropile with a tight packing of unmyelinated axon processes. The two lobes of the brain are connected together by transverse commissure. The neuropiles were insinuated by groups or bundles of giant axons and mesenchymal processes. Cells and axon processes of the O. viverrini brain were rich in tight accumulations of abundant neuronal mediator vesicles. Numerous synaptic contacts were present in the neuropile of brain and scattered in transverse commissure. The organization of the brain of this liver fluke brain was comparable to other trematodes.