Distribution and ultrastructural characteristics of Feyrter cells in the rat and hamster airway epithelium.

Feyrter cells were found both singly and in groups at all levels of the respiratory tract studied in both rats and Syrian golden hamsters. Particularly large and prominent groups of Feyrter cells were present at bronchiolar bifurcations and bronchiolar-alveolar junctions. Single Feyrter cells were also found throughout the respiratory tract, but their distribution appeared entirely random. In all cases examined the groups of Feyrter cells were overlaid by intermediate and serous secretory epithelial cells. Occasionally small areas of the Feyrter cells were exposed to the airway lumen. Small canaliculi-like intercellular spaces were present between adjacent Feyrter cells. Single unmyelinated axons which contained neurotubules, mitochondria, and vesicles were occasionally seen in close association with Feyrter cells.