Mucociliary transport is one of the most important defense mechanisms
of the airway. Mucociliary transport time or rate, as measured using t
he saccharin test or the radioisotope technique, respectively is clini
cally the most relevant parameter although subject to large intra-and
interindividual variability. There is no correlation between mucocilia
ry transport in vivo and ciliary beat frequency ex vivo. Preliminary e
vidence demonstrates that mucociliary transport correlates with ciliar
y structure and orientation as investigated with transmission and scan
ning electron microscopy. A correlation is presented be tween ciliary
beat frequency and secondary ciliary abnormalities. This correlation c
an best be described according to the logistic sigmoid model (r = 0.69
). Based on these functional data, an ultrastructural distinction is p
roposed among normal (less than 5%), light (5 to 15%), moderate (15 to
25%), and severe (more than 25%) secondary ciliary dyskinesia.