Fine structure of tracheo-bronchial epithelial nerves of the cat.

The nerves in and immediately under the epithelial layer of the trachea and primary bronchi of the cat are studied with the electron microscope. The axons are unmyelinated and contain microtubules and mitochondria. Epithelial axons are observed throughout the entire epithelial layer, but, are usually concentrated in the basal area immediately above the basal lamina. Most axons are near the basal cells; others are in the vicinity of granulated cells or occur in the intercellular spaces between other columnar cells. A few of the epithelial axons are large and crowded with axoplasmic mitochondria. The possibility that some epithelial axons may have sensory functions is discussed.