pseudostratifiedoften

Pseudostratified epithelium, often described as pseudostratified columnar epithelium, is a type of epithelial tissue that appears multilayered because nuclei are at different levels, yet every cell rests on the basement membrane, making it actually a single layer. The cells vary in height, and some do not reach the apical surface. Many cells are tall and columnar; goblet cells may be present and secrete mucus. In ciliated forms, apical surfaces bear cilia.

Common forms and locations: The best-known form is pseudostratified ciliated columnar epithelium, found lining much of the respiratory tract, including the nasal cavity, pharynx, larynx, trachea, and bronchi. This tissue often includes goblet cells and uses cilia to move mucus. Non-ciliated variants occur in parts of the male reproductive system, such as the epididymis and vas deferens, where cells can have stereocilia rather than true cilia and contribute to absorption and secretion.

Function: Provides protection and, in ciliated variants, participates in the mucociliary escalator to cleanse airways and luminal surfaces. Secretory goblet cells contribute mucus that traps particles.

Development and clinical notes: Pseudostratified epithelia may be mistaken for stratified epithelia in routine histology. Smoking can cause metaplastic changes, shifting toward a simpler stratified squamous epithelium in some regions, affecting function.