The Nikon MicroscopyU confocal microscopy image gallery was created with a PCM-2000 confocal scanning system interfaced to a Nikon Eclipse E600 upright microscope. Images were recorded in successive z-axis serial sections with C-Imaging Systems software with excitation illumination provided by an argon-ion and/or a helium-neon laser.

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View a higher magnification confocal sequence of mammalian trachea.

The trachea or windpipe, is a part of the respiratory system and is comprised of a long slender tube that carries air to and from the lungs. In addition to serving as a passageway for air, this channel humidifies (moistens and warms) air before it reaches delicate lung tissue, and protects the respiratory tract from foreign particles. A series of 16 to 20 horseshoe-shaped cartilage rings are distributed at various intervals down the length of the tube. Because the trachea is loosely confined by a series of cartilage rings, as opposed to being enclosed within a cartilage sheath, the tube retains flexibility and is able to stretch and contract with breathing.

The windpipe begins by extending downward from a structure that contains the vocal cords referred to as the larynx -- more commonly known as voice box or Adam's apple. When exercising the skill of speech, the chords vibrate as air passes over them to produce sound. Close behind the windpipe is another long tube referred to as the esophagus that provides passage for food and drink to the stomach. In order to prevent food from entering the air passages of the larynx and trachea, a leaf-shaped flap of tissue, the epiglottis, closes the opening into the larynx during swallowing. The human trachea is about five inches long and about half of its length extends into the chest cavity and the rest is in the neck. The windpipe eventually branches into two principal bronchi, one for the right lung and one for the left, which extend and refine before connecting to lung tissue to transfer oxygen.