These are normal cilia of the airways viewed by scanning electronic microscopy. Goblet cells can be seen between the ciliated epithelial cells.
Bacteria that have entered the airways are removed by brisk ciliary motion.
A cross-section of the respiratory tract tissue.
Covered by a mucous layer, we can see ciliated epithelial cells and goblet cells.
The lamina propia mucosae below them are rich in connective fibers such as collagen and contain blood vessels. Even if the bacteria get into the airways, neutrophils that have migrated from the blood vessels encapsulate and remove them.
However, when infected by the highly tissue-invasive influenza virus,
the cilia are desquamated and the mucosal epithelia are destroyed. Tissues without a barrier are destroyed is vulnerable to bacterial invasion.
When bacteria in an influenza patient cause secondary infection, this can trigger pneumonia and sometimes even result in death. Also, a secondary infection by Streptococcus pneumoniae can easily become very serious.
We created an infection model and observed the effect of the antibacterial action of Levofloxacin on the airways mucosa.
We injected the influenza virus, then Streptococcus pneumoniae on day 3.
Levofloxacin was administered for four days starting two hours after the dose of Streptococcus pneumoniae. On day 10 of the infection, the results were compared with those in an untreated group.
First of all, the subject was infected with the influenza virus through the nose.
What we see is the respiratory tract directly above the bronchial bifurcation.
In a normal respiratory tract, the motion of the cilia is quite brisk.
When we focus on the lamina propria mucosae, we can see the mucus flow. The mucus, which has picked up tiny particles and bacteria, is designed to protect against infection by means of ciliary motion that removes the source of infection.