Plasmodium ovale: Morphology: Difference between revisions
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<span style="font-size:90%">The sexual replication form (very distinctive). | <span style="font-size:90%">The sexual replication form (very distinctive). | ||
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<span style="font-size:90%"> | *<span style="font-size:90%">Red cells are very large and have ovoid or distorted forms | ||
*<span style="font-size:90%">[[Macrogametocytes]] (female form) will often entirely fill the erythrocyte | *<span style="font-size:90%">[[Macrogametocytes]] (female form) will often entirely fill the erythrocyte | ||
*<span style="font-size:90%">[[Microgametocytes]] (male form) have a cytoplasmic rim with visible Schüffner's dots | *<span style="font-size:90%">[[Microgametocytes]] (male form) have a cytoplasmic rim with visible Schüffner's dots | ||
Revision as of 21:32, 15 December 2024
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Morphology of Plasmodium ovale
(See Malaria Biology pages for an explanation of these stages)
The early trophozoite
During this later growth stage the rings enlarge and begin to modify the erythrocyte, forming typical features of the species.
- Large and robust-appearing rings, not usually multiply infected
- Red cells may become enlarged and may be ovoid or have a fimbriated apearance
- James' dots (indistinguishable from Schuffner’s dots) often appear
- Pigment will not generally be present at the early trophozoite stage
The late trophozoite
During this growth stage parasites grows but generally retain a ring shape, this process is accompanied by further modification of the red cell with ovoid and fimbriated features more common; metabolism of haemoglobin causes malaria pigment to form.
- Parasites become larger and thickened, but the ring form is generally retained
- Red cell enlargement is seen and distortion causing ovoid and fimbriated forms
- James’ dots will now be prominent in appropriately stained specimens
- Pigment will now be seen over the surface of the parasite
The schizont
The asexual stage of malaria parasite development - only some trophozoites form schizonts, but those that do undergo successive cycles of replication within the red cell to generate multiple "merozoites" that then each invade a new red cell to continue and increase the infection.
- A range of maturing schizonts will generally be present within moderately enlarged red cells
- When mature schizonts may contain 16-24 separate merozoites
- James' dots can be detected in any residual cytoplasm of the erythrocyte
- malaria pigment is visible in irregularly distributed clumps over the schizont surface
The gametocyte
The sexual replication form (very distinctive).
- Red cells are very large and have ovoid or distorted forms
- Macrogametocytes (female form) will often entirely fill the erythrocyte
- Microgametocytes (male form) have a cytoplasmic rim with visible Schüffner's dots
- malaria pigment is clumped evenly over the surface of the gametocyte