Lung disorder. Researcher Estelle Escudier using a transmission electron microscope (TEM) to examine pulmonary cilia in primary ciliary dyskinesia (PCD), a rare genetic lung disorder. The cilia are seen in section in the circular display area at lower left. Other samples are seen at lower right. Cilia are hair-like structures that line the lungs and other organs. In the lungs, they should move in a continuous wave to clear mucus and dust and bacteria from the lungs. In PCD, the cilia do not function properly, causing respiratory problems. Identification of the genes responsible for PCD is being aided by comparisons with the genome for the Chlamydomonas rheinhardtii alga. Photographed in France.