Histology: 4 Main Types of Tissues

Simple squamous epithelium

• Function: Diffusion and filtration where protection is not important; secretes lubricating substances in serosae.

• Location: kidney glomeruli; air sacs of lungs; lining of heart, blood vessels, and lymphatic vessels; lining of ventral body cavity (serosae).

Simple cuboidal epithelium

• Function: Secretion and absorption.

• Location: Kidney tubules; ducts and secretory portions of small glands; ovary surface.

Simple columnar epithelium

• Function: Absorption; secretion of mucus, enzymes, and other substances; ciliated type propels mucus (or reproductive cells) by ciliary action.

• Location (nonciliated): Lines most of the digestive tract (stomach to rectum), gallbladder, and excretory ducts of some glands.

• Location (ciliated): Lines small bronchi, uterine tubes, and some regions of the uterus.

Pseudostratified columnar epithelium

• Function: Secretion of substances (mucus); propulsion of mucus by ciliary action.

• Location (nonciliated): Male’s sperm-carrying ducts and ducts of large glands.

• Location (ciliated): Lines the trachea, most of the upper respiratory tract.

Stratified squamous epithelium

• Function: Protects underlying tissues.

• Location (nonkeratinized): Forms the moist linings of the esophagus, mouth, and vagina.

• Location (keratinized): Forms the epidermis of the skin (dry membrane).

Stratified cuboidal epithelium

• Function: Protection.

• Location: Largest ducts of sweat glands, mammary glands, and salivary glands.

Stratified columnar epithelium

• Function: Protection; secretion.

• Location: Rare in the body; small amounts in male urethra and in large ducts of some glands.

Transitional epithelium

• Function: Stretches readily and allows expansion of urinary organs by contained urine.

• Location: Lines the ureters, urinary bladder, and part of the urethra.