Red cells indexed according to shared functional or structural features
From www.haematologyetc.co.uk
Circulating erythrocytes from early stages of maturation

Early maturation forms may be seen either in physiological or pathological states. It is important to recognise when this is abnormal.
Abnormalities of red cell size or haemoglobin content

Microcytosis is most commonly seen in iron deficiency or thalassaemia. Macrocytosis is more complex with other changes to red cell form often present.
Abnormal cell forms associated mainly with haemoglobinopathy

A miscellaneous set of appearances arising exclusively in the presence of abnormal haemoglobin resulting in sharp ended irregular shapes or inclusions
Abnormal shapes but with rounded and regular form, usually reflecting cytoskeleton or membrane damage

Defects of cytoskeleton or membrane (inherited or acquired) cause diffuse damage that leads to cells with abnormal but regular shape.
Damaged cells with irregular shape or irregular haemoglobin distribution

A group of disorders arising from a range of causes that often indicate significant underlying pathology so require careful consideration.
- Target cells
- Stomatocytes
- Irregularly contracted cells
- Hemighost cells
- Teardrop cells
- Fragmented cells
Cells with two or more projections (spiculated erythrocytes)

Characterised by projections from their surface - but each carrying a very different significance and sometimes indicating severe underlying disease.
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Erythrocytes with inclusion bodies

Red cell types containing single or multiple basophilic inclusions - the nature of the inclusion has considerable diagnostic significance.