A microscope image showing clara cells (green), neuroepithelial
cells (red) and SPNC cells (blue) in foetal mouse airway
epithelium. All of these cells protect the respiratory system
from invading microbes. Image: Riken CDB Researchers have shown
that Notch signalling controls the differentiation and
distribution of lung epithelial cells in the mouse. Nestled deep
within the body, the epithelial lining of the respiratory system
is nonetheless seriously exposed. Its direct contact with
environmental air necessitates protective mechanisms that both
seal off the respiratory tract from other compartments of the
body and neutralise microbial invaders. This is achieved by the
coordinated action of the functionally specialised various cell
types that make up the lining of the airway. These respiratory
cell populations include major ciliated cells, exocrine Clara
cells, and neuroendocrine (NE) cells, all of which are generated
by a common epithelial progenitor cell type during
embryogenesis. One interesting feature o