Stratified epithelium cells (copy)

Stratified Squamous Epithelium

Basal layers with cuboidal shape

Apical cells with squamous shape

Protects against abrasion and friction

Stem cells in basal layer continuously divide

• Replace lost cells at surface

Exists in keratinized and nonkeratinized forms

Keratinized Stratified Squamous Epithelium -

Superficial layers of dead cells

– Cells lack nuclei, filled with keratin

– Cells in basal region migrate toward apical surface

– Fill with keratin and die

– Found in epidermis

Nonkeratinized Stratified Squamous Epithelium

All cells alive

Kept moist with secretions (for example, saliva, mucus)

Lack keratin, protective protein

Microscopically visible cell nuclei

Lines:

• Oral cavity, part of pharynx, esophagus, vagina, anus

Keratinized Stratified Squamous Epithelium - Function

Nonkeratinized Stratified Squamous Epithelium - Function

Stratified Cuboidal Epithelium - Structure

Superficial cells cuboidal in shape

Forms tubes and coverings

Protection and secretion

Forms walls of ducts in most exocrine glands

• Sweat glands, parts of male urethra, periphery of ovarian follicles

Stratified Cuboidal Epithelium

Transitional Epithelium

Limited to urinary tract

In relaxed state

• Basal cells cuboidal; apical cells large and rounded

In stretched state

• Apical cells flattened

Binucleated cells (two nuclei)

Allows for stretching as bladder fills

Transitional Epithelium - relaxed

Transitional Epithelium - distended