To follow the larval developmenl of Eurytrema coelomaticum (Giard & Billet, 1892) in Bradybaena similaris (Férussac, 1821) snails were separated in three classes using the shell diameter: Class A (14.5-10.2 mm), Class B (10.1-6.9 mm) and Class C (6.8-2.6 mm). Only snails belonging to classes A and B acquired the infection. Specimens of E. coelomaticum removed from the pancreatic ducts were exposed to three physiological solutions: Earle, Locke and saline 0.85%, to obtain eggs for the experimental infections, The Locke solution induced the best egg release. The route of migration the intramolluscan development of E. coelomaticum was studied with the aid of histology. The minimal period of intramolluscan developmenl, ending at the expelling of daughter sporocysts, was 107 days for the snails infected in March, and 79 days for the snails infected in November. The Student "t" test and the Chi-square test showed a significant difference (α = 5%) between the two periods, although the mean temperature registered during the experiments did not significantly differed (α = 5%). The elimination of daughter sporocysts occurred through the snail's pneumostome, and always at night. Most sporocysts were eliminated at intervals that varied between one to three days, without regularity. The time of elimination of the daughter sporocysts was different for the two infection period studied: 12 weeks for the snails infected in March, and three weeks for those infected in November. Positive correlation between the number of sporocysts expelled by the snail host and higher temperatures registered in the laboratory was observed. This correlation was more evident in November infection.
Eurytrema coelomaticum; Bradybaena similaris; intramolluscan development; route of migration; sporocyst elimination rhythm