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Epithelial Tissues

Features


Functions

Classifications

Epithelial tissues are classified according to the arrangement, shape and function of their cells.

Arrangement of Cells

Shape of cells


Examples of Epithelial tissues

Simple Squamous Epithelium

Squamous epithelium slide

Identifying features

Single layer of thin irregularly shaped cells, with centrally located nuclei.

Function

Allows movements of substances through membranes such as filtration or rapid diffusion of gases.

Location

Alveoli in the lungs, lining of lymph and blood vessels, glomerulus of kidney, serous membranes.

Simple Cuboidal Epithelium


cuboidal epithelium slide

Low magnification image

Note: centrally located nuclei.
cuboidal epithelium slide

High magnification image

Note: cells in upper right hand corner show typical cuboidal shape.

Identifying features

See notes above

Functions

Location

Lining of kidney tubules, lining of glands, surface of ovary.

Simple Columnar Epithelium

columnar epithelium slide
Note: The columnar epithelium is the lower half of the (purple) tissue.

Identifying features

Column shaped cells, nuclei located in the lower 1/3 of cell. Often this tissue has cilia and goblet cells present (not seen here).

Functions

Location

Lining of digestive tract (from stomach to rectum). Lines uterine tubes and parts of uterus. Lines some of the smaller bronchii.

Pseudostratified Epithelium

pseudo-stratified epithelium slide

Identifying features

These cells appear stratified or layered but are not. Cells all reach the basement membrane, but some may not contact the free surface. Note nuclei in a row at the bottom of the tissue, but also scattered throughout. Cell walls hard to see in this image. Often possess cilia (seen here on outer -top- surface) and goblet cells (also visible).

Functions

Location

Lining of trachea, parts of reproductive system (male urethra), ducts of some glands.

Stratified Squamous Epithelium

stratified squamous epithelium slide
Note: Tissue is the darker purple band making up roughly the central third of the image.

Identifying features

Many layers of cells, therefore quite thick. Individual cell walls are not visible, cells are indicated by nuclei. Usually 10+ layers thick.

Function

Protection

Location

Outer epidermis of skin, lining of anal canal, lines esophagus, pharynx, mouth and vagina.

Transitional Epithelium

transitional epithelium slide
note: Low magnification. Tissue is darker band roughly halfway down image -lower half of tissue.
transitional epithelium slide
note: High Magnification

Identifying features

Several layers thick, cells change shape as tissue is distended. Cell walls not visible, so count the individual nuclei to determine the number of layers of cells. In this image, the tissue is 3 -4 cells thick.

Functions

Location

Lining of parts of urinary tract: parts of urethra, ureter and bladder.

Tissue Index