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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Back to the first confocal sequence of mammalian trachea.

The trachea also commonly known as windpipe is the main air passageway that leads to the lungs. The slender tube extends about five inches in length and has a diameter measuring less than one inch. The interior is lined with a mucous membrane comprised of cells that project fine hair-like structures referred to as cilia. These numerous minute projections serve to sweep dust and foreign particles away from the lungs in upward strokes as they beat in unison. The delicate tissue lining the channel is kept moist by cells and ducts that secret mucus droplets and water molecules. Many blood vessels integrate the lining to warm the incoming air supply and provide pathways for nutrients as well as waste removal. Lymphatic vessels further remove foreign particles that collect along the surface of the wall.

The windpipe forms two branches -- one leads to the right lung and the other to the left. The dual bronchi further divide into smaller and smaller tubes to eventually form tiny tubules referred to as bronchioles. These minute air passages range from three to less than one millimeter in diameter. The tiny airways are quite permeable and contain a well-developed layer of smooth muscle cells that are capable of narrowing the passageways. In this elaborate system, the tubes eventually lead into tiny air sacs called alveoli, which are richly supplied with fine thin walled capillaries. Gases such as oxygen transpire through the permeable capillary membranes to reach red blood cells that circulate oxygen to individual body cells. When the minute alveoli become inflamed due to viral, bacterial, or fungal infection, the condition is referred to as pneumonia.