Cultivation of Schistosoma mansoni in vitro. III. implantation of cultured worms into mouse mesenteric veins.

By injection into mice we assessed the potential for full development and oviposition of young schistosomules, juveniles, and paired adults of Schistosoma mansoni, all grown in vitro from cercariae. Schistosomules 2-hr or 13-days-old were injected into mice via the tail vein; older worms were implanted surgically into the ileocolic vein. Also implanted were previously ovigerous adult pairs that had been perfused from mice and maintained in culture up to 53 days. Eventually, all were capable of producing viable eggs except the worm-pairs that had been grown to the adult stage in vitro; these failed to grow or develop further when implanted into mice. We concluded that pairs once mature in vivo could regain the capacity for oviposition even after prolonged maintenance in vitro, but worms grown entirely in vitro to pairing may have missed some required stimulus which cannot be furnished later, even by an adequate animal host.