Erythrocytic or Endo-erythrocytic Cycle of Malarial Parasite - QS Study

Each cryptomerozoite makes its way into a red blood corpuscle and feeds on its contents. After some time, Endo-erythrocytic Cycle of the parasite gets an amoeboid shape. This growing stage is known as the trophozoite stage. Soon it develops a vacuole which gradually increases in size. Thus the nucleus is pushed to one side. This stage is called the signet ring stage. With further growth the vacu-ole disappears and the amoebula occupies the entire interior of the corpuscle. This stage is known as the schizont stage.

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In the schizont, the nucleus breaks up into bits (6-24) and each be-comes surrounded by a small amount of cytoplasm. These cells are known as merozoites. By the rupture of the wall of the red blood corpuscles the mero-zoites along with wastes(haemozoin) are released into the blood. This causes the malarial fever. The liberated merozoites attack another set of corpuscles and start the life cycle anew. This method of infection is known as autoinfec-tion. The life cycle in the blood of man is called the cycle of Golgi or schizogony or endoerythrocytic cycle.

Schizogony keeps up the multiplication of the parasites and their main-tenance in the blood.

After schizogony has taken place for several generations some of the meroziotes which invade the red corpuscles, instead of developing into tro-phozoites and schizogonts, develop into gametocytes. The gametocytes are of two types – marco-gametocytes and micro-gametocytes. The macro-gametocyte has a small nucleus and a dense food laden cytoplasm. The mi-cro-gametocyte has a relatively large nucleus and clear cytoplasm. Their fur-ther development depends on their entry into the stomach of a female anoph-eles. If it does not take place they disintegrate.