Scanning electron microscopical observations on damages on tegument and gut epithelia of Pagumogonimus skrjabini caused by praziquantel

The Pagumogonimus skrjabini adult worms obtained from experimentally infected dogs were observed under scanning electron microscope 24h after ig praziquantel. At 80 mg/kg the worm body and its suckers obviously contracted, the tegument and the sensory papillae swelled and ulcerated, and the spines broke. The lamellae on the surface of the gut epithelia adhered and the secretory body disappeared. At 120 mg/kg the worm body contracted into dumbbell-like shape or rolled up. The suckers markedly contracted and ulcerated around them and the tegument became ulcerative. The lamellae on the gut epithelial surface which looked like a honeycomb vanished completely and large clump-shaped structures developed. The results of our observations showed that praziquantel, 80 mg/kg to 120 mg/kg, had lethal effect on Pagumogonimus skrjabini adult worms.