Gliding motility of Plasmodium berghei sporozoites. Four differential interference contrast images of sporozoites moving on a glass surface in a nearly perfect circular fashion and models illustrating the current understanding of sporozoite pellicle structure and molecules involved in motility. Scale bar: 10 μm. Arrowheads indicate the tip of the respective sporozoite and numbers indicate time in seconds. The black box indicates the apical (front) part of a sporozoite that is schematically illustrated in the cartoon. Shown are the polar ring (red) that organizes microtubules (green) and gates the secretion of rhoptries (magenta) and micronemes (light blue), the plasma membrane (dark blue) and the IMC (yellow). The green arrowhead points to the microtubule, which is localized away from the other microtubules. The black box at the right enlarges a view of the parasite pellicle to the right. The actin filaments (red) are located between the plasma membrane (PM, blue) and the inner membrane complex (IMC, yellow) and linked to trans-membrane receptors of the TRAP family (light blue) via the glycolytic enzyme aldolase (brown), while myosin (magenta) is linked via a complex of proteins (pink) to the inner membrane complex (IMC, yellow). The microtubules (MT, green) are linked to the IMC by linker molecules (grey). The long grey bars indicate the sub-pellicular network.