columnar epithelium

Examples of columnar epithelium in the following topics:

• Types of Epithelial Tissue

  • The four major classes of simple epithelium are: 1) simple squamous; 2) simple cuboidal; 3) simple columnar; and 4) pseudostratified.
  • Simple columnar epithelium is a single row of tall, closely packed cells, aligned in a row.
  • These are simple columnar epithelial cells whose nuclei appear at different heights, giving the misleading (hence pseudo) impression that the epithelium is stratified when the cells are viewed in cross section.
  • Stratified epithelia can be columnar, cuboidal, or squamous type.
  • Columnar epithelium has cells taller than they are wide.

• Female Duct System

  • There are two types of cells within the simple columnar epithelium of the Fallopian tube.

• Tonsils

  • The tonsils are made of secondary lymphoid tissue and covered with an epithelium characteristic of the part of the body where they are located.
  • For example, the adenoids and tubal tonsils are covered with the ciliated psuedostratified columnar epithelium of the nasopharynx, while the palatine and lingual tonsils are made up of the non-keratinized stratified squamous epithelium of the oropharynx.

• Histology of the Large Intestine

  • The wall of the large intestine is lined with simple columnar epithelium.
  • The crypts and intestinal villi are covered by epithelium that contains two types of cells: goblet cells that secrete mucus and enterocytes that secrete water and electrolytes.
  • The enterocytes in the mucosa contain digestive enzymes that digest specific food while they are being absorbed through the epithelium.
  • Also, new epithelium is formed here, which is important because the cells at this site are continuously worn away by the passing food.

• Trachea

  • It is lined with pseudostratified ciliated columnar epithelium cells with goblet cells that produce mucus.
  • The epithelium and the mucociliary ladder can be damaged by smoking tobacco and alcohol consumption, which can make pneumonia (an infection of the alveoli of the lungs) from bacteria in the upper respiratory tract more likely to occur due to the loss of barrier function.
  • A cross section of the trachea, showing the hyaline cartilage, mucus glands, and ciliated epithelium.

• Nose and Paranasal Sinuses

  • The paranasal sinuses are a group of four, paired, air-filled spaces, lined with respiratory epithelium (ciliated columnar epithelium).

• Skin and Mucosae (Surface Barriers)

  • The most variation is seen in the epithelium.
  • In the stomach it is columnar and organized into gastric pits and glands to secrete acids and pepsin.
  • The small intestine epithelium is specialized for absorption, organized into simple columnar epithelium on protruding villi with narrow crypts that have a high surface area.
  • The mucosal epithelium in the nasopharynx is psuedostratified and ciliated, which helps accumulate and remove mucus.
  • Not every pathogen is caught nor inhibited in mucus, and some may infect the mucosal epithelium directly.

• Mucosa

  • The mucosa, composed of simple epithelium cells, is the innermost layer of the gastrointestinal (GI) tract.
  • It is composed of epithelium cells and a thin connective tissue.
  • The most variation is seen in the epithelium tissue layer of the mucosa.
  • In the esophagus, the epithelium is stratified, squamous, and non-keratinizing, for protective purposes.
  • In the stomach. the epithelium is simple columnar, and is organized into gastric pits and glands to deal with secretion.

• Testes Ducts

  • The epithelium of the tubule consists of tall, columnar cells called Sertoli cells.
  • The ductuli are unilaminar and composed of columnar ciliated and nonciliated (absorptive) cells.
  • The epithelium is surrounded by a band of smooth muscle that helps to propel the sperm toward the epididymis.

• Epithelial Membranes

  • The mucous membranes are linings of mostly endodermal origin, covered in epithelium, which are involved in absorption and secretion.
  • It consists of an epithelium layer and an underlying lamina propria of loose connective tissue.
  • Most mucous membranes contain stratified squamous or simple columnar epithelial tissue.