Often you will see cells in orderly arrangements.

When cells adhere to one another in order to cover an interior or exterior surface, we call them epithelium. The cells are attached tightly to one another to protect the integrity of the surface and keep tissue fluids from leaking out.

Epithelial cells cover every healthy body surface except the gliding surfaces of joints and the surfaces of the teeth.

Epithelial cells stick tight to one another. There are many different kinds of epithelium.

Beginning students are often disappointed that they cannot always see the cell borders. This should not surprise you. Often they are only a few molecules thick. Also remember that animal cells do not have cell walls.

This photo shows a group of cells, adherent to one another and forming a ring. The cell borders are just barely visible. Don't be concerned if you cannot see them.

This is a pancreatic duct. Its inner surface is lined (as almost all surfaces must be) by an epithelium which makes up most of its thickness. Surrounding the epithelium are strands of collagen which are continuous with the surrounding fibrous tissue.

With your study partners, find:

• the epithlium of the little duct; notice both cytoplasm and nuclei


• the fibrous tissue, with many strands of collagen surrounding the duct

United States Pronunciations:

• Epithelium: EPP-ih-THEE-lee-um (unvoiced th)

Roots:

• epi: on


• thelium: layer


• duct: guide

Fun to know:

Medical singular words that end in -um usually form plurals in -a (not -ae).

epithelium, epithlia
septum, septa (not septae)
trabeculum, trabecula (not trabeculae)
diverticulum, diverticula (not diverticulae)

Medical singular words that end in -a usually form plurals in -ae.

glabella, glabellae
lamella, lamellae

Next
Previous
Image List
Kansas City University of Medicine and Biosciences