Fig. 1.

Schistosoma mansoni miracidia (t=0 h) as they undergo morphological transformation to the primary sporocyst stage (t=24 h). Miracidia, cultured in isotonic snail saline (Chernin’s balanced salt solution, CBSS; Chernin, 1963), first cease swimming, assume a rounded shape (t=2 h) as expansion of intercellular ridges force ciliated epidermal plates to round up and detach from the larval surface (t=6 h). ‘t’ indicate the approximate time elapsed from initial introduction of miracidia into culture.