Tracheobronchial clearance in health and disease: with special reference to interciliary fluid

Rats were exposed to influenza B virus for 2 hours. Mucociliary function in the isolated airway preparation of these animals was studied from the first day after exposure and at regular intervals for up to 190 days. Transmission electron microscopy (TEM) studies were done at times corresponding to the mucociliary function studies. TEM studies confirmed the results of the mucociliary function studies: pathological changes were first apparent three days after exposure and began in the distal bronchioles. The morphological studies further demonstrated that the infection progressed proximally to include the entire tracheobronchial tree by the 18th day. The alterations observed included an increase in the number of goblet cells, a decrease in the number of microvilli and a reduction in the amount of interciliary fluid. The last two changes were closely correlated with the severity of the infection. The abnormalities found in mucociliary function included hypersecretion of mucus, inactive and hypoactive zones, synchronization of cilia beating, and a sticking together of the cilia tips.