trachea cellsCultured cells from the trachea of a child with asthma. Cell nuclei are stained blue. The green rings show tight junctions that attach the cells to each other and form a physical barrier, protecting tissues from airborne particles like pollen and bacteria. The tight junctions shown here appear to be compromised after infection with the common cold virus. This would make the barrier less effective.

Visualised using confocal microscopy by Alysia Buckley, University of Western Australia.

Size: the cell nuclei are 4–5 micrometres in diameter.

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