P. falciparum undergoes continuous change during its life cycle. It begins as a sporozoite which is spindle-shaped and 10-15 μm long. In the liver it grows into an ovoid schizont of 30-70 μm in diameter. Each schizont produces merozoites, each of which is approximately 1.5 μm in length and 1 μm in diameter. While in the erythrocyte, the merozoite forms a ring-like structure and becomes a trophozoite. The trophozoite feeds on hemoglobin and forms a granular pigment called haemozoin.
The two images on the right show P. falciparum ring-like structures. Top image is a thick smear while the bottom one is a thin smear.
A unique feature to P. falciparum is that the gametocytes are elongated and crescent-shaped (image below). A mature gametocyte measures 8-12 μm long and 3-6 μm wide. The ookinete is also elongated and measures roughly 18-24 μm. The oocyte is rounded and can grow up to 80 μm in diameter. The ookinete and oocyte are mosquito forms and are thus not seen in the blood.
Images courtesy for the CDC.https://www.cdc.gov/dpdx/malaria/index.html
