Simple Epithelial Tissues

Simple Cuboidial Epithelium
Simple Cuboidial Epithelium
Description: Single layer of cubelike cells with large, spherical nuclei.

Function: Secretion and Absorption.

Location: Kidney tubules; ducts and secretory portions of small glands; ovary surface.
Simple Columnar Epithelium
Simple Squamous Epithelium
Description: Single layer of flattened cells with disc-shaped central nuclei and sparse cytoplasm: the simplest form of Epithelia.

Function: Allows passage of materials by DIFFUSION and FILTRATION in sites where protection is not important; secretes lubricating substances in serosae.

Kidney, air sacs of lungs, lining of heart, blood vessels; lining of ventral body cavity (serosae).
Stratified Squamous Epithelium
DESCRIPTION: Thick membrane composed of several cell layers; basal cells are cuboidal or columnar. Surface cells are flattened/squamous.

KERATINIZED TYPE surface cells are full of keratin and dead: basal cells are active in mitosis.

FUNCTION: Protects underlying tissues in areas subject to abrasion.

NONKERATINIZED TYPE form the moist linings of the esophagus, mouth and vagina.

KERATINIZED forms the epidermis of the skin, a DRY membrane.
Transitional Epithelium
DESCRIPTION: Resembles both stratified squamous AND stratified cuboidal; basal cells cuboidal or columnar; surface cells DOME SHAPED or squamous (depending on degree of organ stretch, like full bladder).

FUNCTION: Stretches readily and permits distension of urinary organ by contained urine.

LOCATION: Lines ureters, bladder and part of urethra.
Pseudostratified Columnar Epithelium
DESCRIPTION: Single layer of cells of differing heights, some not reaching the free surface; nuclei seen at different levels. May contain goblet cells and cilia.

FUNCTION: Secretion of mucus, propulsion of mucus bu cilia.

LOCATION: Non-ciliated type in male's sperm carrying ducts. Ciliated types lines trachea and most of upper respiratory tract.

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