Human Models of Epithelia

Epithelial tissues are composed almost entirely of cells, and are supported by connective tissue. Within epithelial tissues, there are orginizational categories including: simple and stratified. Within those categories, there are also three types: squamous, cuboidal, and columnar.  In this post, our classmates worked together to create human models of the aforementioned epithelial tissues. 

The first model we made was for pseudostratified columnar epithelial tissue. This is a single layer of cells, in which all of the cells are of varying heights. Some cells do not reach the surface, and the nuclei can be seen on different levels. This type of epithelial tissue secretes mucus and propels it through ciliary action. Pseudostratified columnar epithelial tissue can be found lining the trachea and most of the upper respiratory tract. Nonciliated forms of this tissue can be found in male's super-carrying ducts and ducts of large glands.

Transitional epithelial tissue consist of many cell layers in which the cells located at the base are cuboidal and the surface cells are shaped like domes. Translational epithelia can be found lining the urinary bladder, ureters, and part of the urethra, stretching to permit the distension of the urinary bladder. 

The simple squamous is a stout, squished layer of single cells that diffuses and filters. It is used in the lymphatic and cardiovascular systems, creating a thin, slick layer that reduces friction. 

Stratified cuboidal is more uncommon in the body, and is usually 2-3 layers thick. Stratified cuboidal tissue can be found in some mammary and sweat glands.

Simple cuboidal epithelia is another example of epithelia that absorbs and secretes. This type of epithelia is found in the kidney tubules, ovary surface, and ducts and secretory portions of small glands. Simple cuboidal epithelial tissue is composed of a single layer of cube like cells with large, spherical central nuclei. 

Simple columnar epithelia consist of a single layer of tall cells with oval nuclei. Many of these cells contain cilia, which help transport mucus. This layer may also contain mucus-secreting unicellular glands referred to as goblet cells. Located in the digestive tract, gallbladder, and excretory ducts of some glands, nonciliated simple columnar epithelia works to absorb, secrete mucus, enzymes, and other substances. Ciliated simple columnar epithelia is found lining small bronchi, uterine tubes, and some regions of the uterus, working to propel mucus.

Stratified columnar tissue is also not very abundant in the body, however, it can be found in the pharynx, male urethra, lining of some glandular ducts, and transitional areas between 2 types of epithelia.

And thus concludes the lesson on epithelia! Thanks to my classmates and their efforts in making this lesson!