Maintenance In vitro of Larval Schistosoma mansoni in Tissues from the Snail, Australorbis glabratus

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Abstract
Portions of digestive gland and ovotestis were removed from aquarium-reared Australorbis glabratus about 40 days after infection with Schistosoma mansoni. The tissues were minced and explanted in flasks under sterile conditions. The cultures were maintained at 26 to 28 C either on a complex medium, or, with generally superior results, on a balanced salt solution containing glucose and trehalose (BSS). Medium was changed daily and cultures were evaluated by counting the emerged cercariae and by histologic study of the tissues. Apparently normal cercariae emerged daily in relatively large numbers during the 1st week, and in decreasing numbers during the succeeding 1 to 2 weeks. Omission of the sugars from BSS adversely affected the yields of cercariae: addition of amino acid mixtures to BSS did not increase the amount or duration of cercarial emergence. At least in part, cercarial emergence was found to be influenced by light. A small proportion of culture-de rived cercariae was infective for mice by skin penetration or intraperitoneal injection. Tissues harboring "immature" infections were also explanted, i.e., from snails 19 days after exposure to S. mansoni. It was demonstrated that cercarial embryos were capable of undergoing maturation in vitro when cercariae appeared in these cultures after a lag of 8 to 13 days.