pseudostratified epithelium

Examples of pseudostratified epithelium in the following topics:

• Types of Epithelial Tissue

  • Simple epithelium consists of a single layer of cells.
  • The four major classes of simple epithelium are: 1) simple squamous; 2) simple cuboidal; 3) simple columnar; and 4) pseudostratified.
  • Pseudostratified epithelium can also possess fine hair-like extensions of their apical (luminal) membrane called cilia.
  • In this case, the epithelium is described as ciliated pseudostratified epithelium.
  • Stratified epithelium differs from simple epithelium by being multilayered.

• Digestion in the Mouth, Pharynx, and Esophagus

  • It is lined with stratified squamous epithelium.
  • The nasopharynx lies behind the nasal cavity and, like the nasal passages, is lined with ciliated columnar pseudostratified epithelium.
  • Like the oropharynx above it, the hypopharynx (laryngopharynx) serves as a passageway for food and air and is lined with a stratified squamous epithelium.

• Trachea

  • It is lined with pseudostratified ciliated columnar epithelium cells with goblet cells that produce mucus.
  • The epithelium and the mucocilliary ladder can be damaged by smoking tobacco and alcohol consumption, which can make pneumonias (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.

• Pharynx

  • The nasopharynx and associated nasal tissues are lined with ciliated pseudostratified columnar epithelium, excellent for sweeping debris from the nasal passages.
  • The oropharynx is lined by non-keratinized stratified squamous epithelium.
  • Like the oropharynx above it, the laryngopharynx serves as a passageway for food and air and is lined with a stratified squamous epithelium.

• Bronchi and Subdivisions

  • The mucous membrane lining the bronchi also undergoes a transition from ciliated pseudostratified columnar epithelium to simple cuboidal epithelium to simple squamous epithelium further into the lung.

• Mucosa

  • The mucosa is the innermost layer of the gastrointestinal (GI) tract, composed of simple epithelium cells.
  • It is composed of epithelium cells and a thin connective tissue.
  • The mucosa is made up of three layers: epithelium, lamina propria, and muscularis mucosae.
  • 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.

• Characteristics of Epithelial Tissue

  • Epithelia tissue forms boundaries between different environments, and nearly all substances must pass through the epithelium.
  • In its role as an interface tissue, epithelium accomplishes many functions, including:
  • The secretion of sweat, mucus, enzymes, and other products that are delivered by ducts come from the glandular epithelium.
  • There are eight basic types of epithelium: six of them are identified based on both the number of cells and their shape; two of them are named by the type of cell (squamous) found in them.

• Epithelial Tissues

  • This is called pseudostratified, columnar epithelia .
  • Pseudostratified columnar epithelia line the respiratory tract.

• Development of the Integumentary System

  • At four weeks gestation, simple ectoderm epithelium forms.
  • Between four and 12 weeks, the basal cellls divide repeatedly forming the stratified epithelium.
  • Melanoblasts that will form melanocytes migrate with neural crests cells to the epithelium and begin producing melanin prior to birth.

• 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.