Colour of cell cappings

The first observable symptom of AFB is usually a change in the appearance of cell cappings

Healthy cappings (Fig. 8) are raised in shape, and range in colour from light to dark brown.

Figure 8: Healthy cell capping Figure 9: Dark sunken cell capping

Cappings covering infected cells will initially be the same colour as the uninfected cells surrounding them. However, infected cells will eventually become darker in colour until they appear black. Infected cells also develop a moist, almost greasy appearance and become sunken (Fig. 9).

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