ABSTRACT
In the present study,the trachea of 17 new borns and 10 animals, including rabbits, dogs and monkeys were used. The neural elements were visualized by Cajal-Faworsky silver impregnation and osmic acid techniques. Specimens were cut in to sections by freezing microtome and stained by Gros—Bielchowsky method.Branches from the recurrent laryngeal and vagus nerves pass to the trachea,dividing and rejoining to form a mesh-like plexus outer to the cartilage. Fibers of the posterior parts of the plexus appear as a well-defined longitudinal chain of nerves. The branches from this plexus re-form a primary, secondary and tertiary plexuses in the membrane of cartilage plates, in the muscle, the submucous regions and the mucosa.Parasympathetic effector neurons were mostly found in the posterior and lateral wall, on rare occasions the anterior wall.A profuse supply of predominantly unmyelinated fibres innervates the muscle,blood vessels and glands, and the plexuses supplying these structure apparently communicate with each other. They also contain some thinly myelinated fibres.In the layer of smooth muscle the nerve fibres give off fine collaterals and end in knob-like or arrowheaded swellings. The fibres of subepithelial plexuses branch rectangularly and pass between the epithelial cells. All these fibers terminate in knobs which lie among the deep epithelial cells.