Immunization inhibits embryogenesis in female worms.

Mice were immunized three times s.c. with 100,000 Mf in alum. Control mice received alum alone. L. sigmodontis challenge infection was performed one week after the last immunization. Seventy days after infection female worms were analyzed for their embryonic stages. Representative pictures of oocyte (A; micron bar 10 µm), divided egg (B; 10 µm), pretzel stage (C; 15 µm) and stretched Mf (D; 30 µm) are shown. (E) Embryogram illustrating the composition of embryonic stages in female worms. If present, three female worms of each mouse were investigated (27 females in the control group, 28 females from the immunized group, additional experiments see Figure S4). Statistical analysis was performed with Mann-Whitney U-test (mean ± SEM, ** P<0.01, *** P<0.001).