This half-hour program opens in a spectacular setting: The “Red Rocks” region near Morrison, Colorado. In this home to many fossil dinosaurs, Dr. Moran — who enjoys teaching in the beauty of nature — gives an entertaining, extremely lucid description of epithelial tissues and their classification.
Moving to the laboratory, we investigate a variety of tissues using both light and electron microscopes, always starting at low magnification for orientation and easing up to higher magnification for details of cellular organization. At the start of our journey, we see how SIMPLE SQUAMOUS EPITHELIA are organized, using the kidney’s nephron as an example. Then we move on to SIMPLE CUBOIDAL EPITHELIA, looking at the thyroid follicle’s lining by light and electron microscopy. Next, SIMPLE COLUMNAR EPITHELIA are described, viewing a beautiful H&E preparation of the lining of the intestinal villus.
The “Stratified” epithelia — cellular coverings more than one cell layer thick — are then investigated, starting with STRATIFIED SQUAMOUS EPITHELIA. The lining of the esophagus uses this type of epithelium in its non-keratinized form. Skin— much tougher than the esophagus — is used to illustrate the keratinized stratified squamous epithilium. Then, a rather rare epithelial type — the STRATIFIED CUBOIDAL EPITHELIUM (sometimes called “stratified columnar epithelium”) — is investigated, using a stunning Masson’s trichrome preparation of a salivary gland’s duct at low and high magnification.
Next, PSEUDOSTRATIFIED COLUMNAR EPITHELIA are examined, featuring the ciliated epithelia that line the trachea and major airways of the respiratory system. An exceptional Toluidine Blue section is viewed with the light microscope, followed by a most unusual low-magnification serial section photographed by electron microscopy taken from Moran and Rowley’s “Visual Histology” atlas, a companion book to the DVD series (available as a free download on this website).
The last epithelial type we study is the TRANSITIONAL EPITHELIUM lining the bladder. As you can guess from personal experience, the epithelium lining the bladder undergoes a dramatic change in appearance when the empty bladder — a small, collapsed, flaccid bag — accumulates fluid and becomes large and (painfully) full.
Having completed our tour of epithelial tissues, the PRACTICAL EXAMINATION is given in which Dr. Moran asks you pointed questions about specific structures seen during the program, allows you time to respond, and then provides you with a detailed answer. Most students, having watched this half-hour video program, do very well on the practical examination. This makes us very happy!
