ABSTRACT
Microsporidians are intracellular parasites found in a wide range of phyla with a high incidence of host species particularly in the phylum Arthropoda. Microsporidians are eukaryote parasites with a unique infective spore stage which functions as a missile. The microsporidian spore wall has two major parts: an inner 100 mm-thick wall with a significant percentage of chitin; and a 15 to 20 nm-thick outer wall. Bound calcium will move into the spores of Glugea hertwigi and Spraguea lophii and trigger spore activation and discharge with the immersion of the spores into an appropriate hatching medium. There is a calcium influx during spore activation; this calcium movement is blocked with micromolar verapamil, the calcium channel blocker. There is some evidence that the discharging polar filament protein from microsporidian spores undergo a chemical change from a monomeric, fluid state to a rigid, polymeric assemblage at the site of the growing tip of the tube.
