Objective To observe the development of Schistosoma japonicum after single sexual infection and double sexual infection respectively. Methods A single Oncomelania hupensis snail was infected by a single schistosome miracidium. The larva were induced and released from the snail after 60-day incubation at 26 ℃. The mice were infected by the larva(single sexual infection)and dissected 40 days after the infection. All the worms were collected and the sex of the larvae was determined by the sex of the adult worm...