(A) The different developmental stages of Nosema ceranae. The developmental stages include meront (M), sporont (ST), sporoblast (SB), and mature spore (MS). MB = Membrane of the infected host cell. (B) Electron-micrograph of longitudinal section of Nosema ceranae spore showing (a) anchoring disk (AD), polaroplast (P), posterior vacuole (PV), polar filament (PF); (b) endospore (EN), exospore (EX), plasmamembrane (PM), nucleus (N), 20–22 isofilar coils of the polar filament (PFs); and (c) extruded polar filament (EPF) (From Chen et al., 2009a).