There are different types of cells in the body. Of these, the epithelial cells are lined up against the surface of the skin, and also along the linings of various internal organs. The epithelial cells are one of the four basic cell types of animal tissues.
They are in turn classified according to the morphology as simple, stratified, and pseudostratified epithelial cells. The columnar epithelial cells are a type of simple epithelial cells.
The height of columnar epithelial cells is about 4 times their width. They have an elongated nucleus, which is located towards the base of the cell. They are found in the lining of the stomach and intestines. A few of them are present inside reproductive organs, several glands, and places in the body where secretion and absorption takes place.
The ones present in respiratory tracts are found to have small hair-like structures called cilia. Cells in intestines have microvilli, which help in increasing the surface area for absorption. Between them, there are tiny goblet cells present. They are also present in respiratory passages. They secret mucus that serves as a protective layer and lubricant.
Simple Columnar Epithelium
The lining of stomach, small intestine, and large intestine are made up of this type of cell. You will also find them in the cervix and uterus. They are divided into two more subtypes: ciliated and non-ciliated cells. The former ones are aligned with the upper respiratory tract, Fallopian tubes, uterus, and the spinal cord.
Their function is to help in the movement of the mucus and other substances along the path of various body organs. They also help in pushing the egg cell through the uterine tube into the uterus.
Stratified Columnar Epithelium
It consists of column-shaped cells, which are arranged in multiple layers. These cells are found in the ocular conjunctiva of the eye, pharynx, mammary gland, salivary gland, uterus, male urethra, vas deferens, and the anus. Their functions include secretion of mucus and protection of the organs, in which they are present.
Pseudostratified Columnar Epithelium
This lining consists of single-layered cells. They have the nuclei placement similar to that of the stratified ones. They are called pseudostratified, as they give an impression as if there is more than one layer of the cells. The ciliated pseudostratified cells are present in the trachea and upper respiratory tract.
The non-ciliated ones are found in the vas deferens, and the cells with stereocilia are present in the epididymis. Their functions include secretion as well as absorption of various body fluids.