Rhoptry secretion of membranous whorls by Plasmodium berghei sporozoites.

Electron microscopy of sporozoites of the rodent malaria parasite, Plasmodium berghei, reveals electron-dense multilaminate membranous whorls within components of the rhoptry-microneme complex after fixation with tannic acid in conjunction with glutaraldehyde. This multilaminate material, which has a dark line to dark line periodicity of approximately 5 nm, appears to be secreted from the sporozoite since it is also found adhering to the sporozoite's external surface. The material may function in sporozoite gliding motility and in invasion of host cells.