Surface specializations comparison
These images compare the appearance of epithelial cell surface specializations: microvilli (left), stereocilia (middle) and cilia (right). Microvilli are about 1 micron in length, non-motile and contain a core of microfilaments. Stereocilia are 20-50 microns in length, and like microvilli, are non-motile and contain a core of microfilaments. Cilia are 10 microns in length, are highly motile and contain a core of microtubules. All images are 1,200x magnification.
This image shows the lining epithelium of the intestine which possesses a dense accumulation of microvilli that collectively form a brush border. Microvilli significantly increase the surface area of the epithelium for absorption.
This image shows the lining epithelium of the epididymis, a region of the male reproductive tract, with prominent stereocilia. Stereocilia are structurally and functionally similar to microvilli but are significantly taller. Stereocilia are not related to cilia.
This image shows the lining epithelium of the trachea with its prominent cilia. Cilia are highly motile and serve to move materials along the surface of the epithelium. In this example, the respiratory epithelium is overall much thinner than the other two examples of epithelia shown.
Goblet cells >
Goblet cells are goblet-shaped unicellular glands that secrete mucus. They are commonly seen in the epithelia of respiratory passages and intestines.