Quantitation of the secretory cells of the ferret tracheobronchial tree.

The tracheal epithelium of the ferret has few goblet cells while sero-mucous submucosal glands are present in large numbers throughout the length of the trachea and bronchi. The epithelium consists mainly of ciliated cells and of dark cytoplasmic non-ciliated cells that sometimes contain secretory granules. Any 'respiratory tract fluid' secreted into the ferret trachea is probably mainly glandular in origin. The epithelium contains neutrophils and a few mast cells and eosinophils. Nerve fibres are virtually absent from the epithelium, and this may be associated with a lack of the cough reflex from the ferret trachea. From a morphological point of view, the ferret trachea may well make a good model for the study of submucosal gland secretions.