Simple Epithelium

1. Simple Squamos Epithelium



Simple squamos(pavement) epithelium consists of a single layer of flat, thin cells. Simple squamos epithelium have horizontally flattened, elliptical nuclei which corresponds to the form of the cell.
The thin nature of this type of epithelium makes it ideal for small molecules(such as respiratory gases) to pass through its membranes through diffusion and filtration.
The simple squamos epithelia is found lining the alveaoli as well as the glomerulus, where rapid diffusion is a required.


2. Simple Cuboidal Epithelium



Simple Cuboidal Epithelium consists of a single layer of cube-shaped cells, that have a spherical nucleus in the centre.
The simple cuboidal epithelium constitute the germinal epithelium which produces the egg cells in the female ovary and the sperm cells in the male testes. They also offer some degree of protection(by actively or passively pumping material in and out of the lumen) and function in absorption and secretion.
The simple cuboidal epithelia are found lining the surfaces of the ovary, nephron and the walls of the kidney tubules.


3. Simple Columnar Epithelium



Simple Columnar Epithelium consists of a single layer of tall column-shaped cells with an elongated nuclei that is located near the base of the cell.The simple columnar epithelia may or may not have cilia, thus dividing them into two categories; ciliated and non-ciliated.
The primary function of the simple columnar epithelium is protection(for instance, this epithelium in the stomach and digestive tract serves as an impermeable barrier against bacteria). The simple columnar epithelia can also specialize to secrete mucus(a mixture of glyprotein and water) which is a slippery substance produced by the mucus membranes. The cilia on the ciliated simple columnar epithelium helps sweep the mucus which traps infectious agents in a certain direction.
The simple columnar epithelia are found lining the stomach and digestive tract as well as the wall of the uterine tube where currents generated by the beating of cilia propel the egg cell towards the uterus.


4. Pseudostratified Columnar Epithelium



Pseudostratified Columnar Epithelium consists of a singe layer of cells with nuclei located at different levels making it seem as though as it is stratified; this is the main reason why it is called pseudostratified(pseudo=false) which literally means falsely stratified. These epithelia may be ciliated or non-ciliated or may contain stereocilia.
The pseudostratified columnar epithelia function in secretion and absorption. The ciliated type are usually involved with the sweeping of mucus.
The ciliated pseudostratified columnar epithelia are found lining the trachea as wee as certain parts of the upper respiratory tract. The non-ciliated pseudostratified columnar epithelia are found in the membraneous part of the male vas deferens. The pseudostratified columnar epithelia with stereocilia are located in the epididymis(part of the male reproductive system). The stereocilia are distinct from cilia but are both closely related.