Pseudostratified columnar epithelium• It consists of columnar cells crowded very

closely together.• In cross section, the nucIei appear to be on two

or more levels and because of the crowding, the cells appear distorted, and they all do not reach the surface.

• But in fact every cell rests on the basement membrane, so the epithelium is technically "simple", in spite of appearances.

Cells that reach the surface are either ciliated or goblet cells

• The goblet cells secrete mucous, which forms a film on the luminal surface of the respiratory passages and prevents duct from being inhaled into the lungs.

• The cillia move the mucous containing the dust particles up and out of the respiratory passages.

• The cells that do not reach the surface probably,serves as progenitor cells producing new cells.

1- Non ciliated pseudostratified epithelium Vas deferens, human - H&E

2- Ciliated  pseudostratified epithelium lines the mucosa of the trachea. Most of the tall (columnar) cells are ciliated, a specialization that allows dust and mucous to be swept upward and eliminated

Psuedostratifed epithelium is classified into:

1- Non ciliated pseudostratified epithelium

Vas deferens, large ducts, male urethra

2- Ciliated  pseudostratified epithelium

• the respiratory tract, e.g. trachea, and

• Epididymis (in the male reproductive system).

Ciliated pseudostratified epithelium, Epididymis

Stratified epithelium:

1.Stratified Squamous Epithelium

2.Stratified cuboidal Epithelium

3.Stratified columnar Epithelium

4.Transitional Epithelium

1. Squamous stratified epithelium

• consists of flattened (squamous) cells on the surface overlying multiple layers of cells that usually are more cuboidal toward the base of the epithelium.

• The innermost layer (stratum germinativum):*Contains basophilic, polyhedral cells.

*metabolically active and show mitotic figures to replace those lost from the outer surface.may contain tonofibrils (the precursors of keratin).  

• Outer layer may be (types of squamous stratified)• keratinized (dead and hardened) on dry surfaces such as skin, . OR

• nonkeratinized on wet, mucous surfaces, are seen in the body opinings such as:

• Mouth, Tongue• Esophagus,• Vagina

Stratified squamous epithelium, keratinizedSkin, epidermis

stratified squamous, keratinized epithelium, plantar skin (H&E)

Artificial spaces

Artificial spaces

Location of the basement membrane

Individual cells of stratified squamous epithelium

Basal layer

Stratified squamous epithelium, non

keratinized, tongue, vertical section

Stratified squamous epithelium, non keratinized Esophagus, mucosa (cross section)

stratified squamous, non/keratinized epithelium, vagina (H&E)

Lumen of vagina

Stratified squamous nonkeratinized epithelium

Basal side of epithelium

Outside lumenal side of epithelium

stratified squamous, non/keratinized epithelium, vagina (H&E)

Cuboidal stratified epithelium

• Contains tow or more layers of cuboidal cells.

• The basement membrane is usually present

• The free surfaces have a distinct borders.

• It is uncommon type

• Is found in the ducts of the sweet glands and in the lining of vesicular ovarian follicles (Graffian follicles)

Cuboidal stratified epithelium, Two Layers This is sweat gland variant with two layers of

cuboidal cells.

Cuboidal Stratified epithelium lining of developing ovarian follicles.

T. s. in mammalian ovary showing, primary and secondary follicles

A magnified previous Cuboidal stratified epithelium

Basement membrane

Membrana granulosa

Cuboidal Stratified epithelium Testis, young and mature - H&E

Columnar stratified epithelium

• Basal layer is cuboidal or spherical cells• Columnar layer is above• Is found on the wet surfaces , where more

protection is required• Is uncommon,• but examples:

**Ciliated (nasal surface soft palate)**Non ciliated (male urethra penis).

Transitional epithelium, • Basal layer is columnar cells• followed by polygonal cells going toward the surface• Then followed by pyriform cells • And eventually by pear-shaped dome cells that are convex on

their free border. These cells contain numerous mitotic figures, large amount of DNA, polypoid nuclei and may be binucleated.

• The basement membrane is not visible in light microscopy.

• The name "transitional" derives from this tissue's ability to change its shape squamous when stretched.

• also called urothelium, is a stratified epithelium lining the distensible walls of the urinary tract.

• Function: distention• Examples:  urinary bladder, ureter

The transitional epithelium is highly magnified:Note that the cells at the exposed surface (A) are large and rounded. They are also larger than the cells at the attached surface (B).

Compare this tissue to Stratified Squamous which has squamous cells at its exposed surface.)

The ureter is lined by transitional epithelium

lumen

Mucosa / submucosa

muscularis

adventitia

ureter (Lee's stain)

Lumen of ureter

Surface cells

Provided slides1. Non ciliated pseudostratified epithelium Vas deferens, t.s.2. Ciliated  pseudostratified epithelium trachea, t.s3. Ciliated  pseudostratified epithelium Epididymis t.s

4. Stratified squamous epithelium, keratinized epidermis skin, v.s.5. Stratified squamous epithelium, non keratinized, tongue, vertical section6. Stratified squamous epithelium, non keratinized Esophagus, mucosa (cross

section)7. stratified squamous, non/keratinized epithelium, vagina t.s.8. Cuboidal stratified epithelium, Two Layers, sweat gland, skin, v.s.

9. Cuboidal Stratified epithelium lining of developing ovarian follicles. Mammalian ovary, t.s.

10. Cuboidal Stratified epithelium, seminiferous tubules, Testis, young and mature – t.s.

11. The transitional epithelium. Urinary bladder, t.s.12. The transitional epithelium, ureter, t.s