Scanning electron microscope observations of Plasmodium berghei ookinetes in primary mosquito cell cultures

Plasmodium berghei-infected blood from mice was inoculated into primary cell cultures (PCC) obtained from the mosquito Anopheles stephensi. Immature and mature ookinetes of Plasmodium berghei, which developed in these cultures were studied with the scanning electron microscope. Immature ookinetes had a bulbous-like structure at the posterior end and a slightly wrinkled surface. Mature ookinetes were smoother in appearance and somewhat longer than immature forms. Shallow spiraling waves were observed on the surface of some ookinetes, especially in the anterior half of the body. Such waves may be involved in ookinete locomotion. Penetration of cultured cells by ookinetes was not observed. Infected red cells, which were present in the inoculum, had small depressions on the red cell surface, whereas some uninfected red cells had accentuated concavities. Mouse blood cells adhered closely to PCC cells; some attached red cells were irregular in shape.