PRACTICAL ROADMAP

EPITHELIUM

A. Jovanović

EPITHELIA

• Simple epithelia

Simple squamous

Simple cuboidal

Simple columnar

Pseudostratified

• Stratified epithelia

Stratified squamous

- non keratinized

- keratinized

Transitional

SIMPLE EPITHELIA

• Slide 66 Choroid plexus

Simple squamous epithelium

Simple cuboidal epithelium

CHOROID PLEXUS

Brain tissue

Choroidplexus

Ventricle

CHOROID PLEXUS

Brain tissue

Vascular choroidplexus

Ventricle

CHOROID PLEXUS

Ependymalcells

Capillary

Ventricle

CHOROID PLEXUS

Simple cuboidal epithelium

(Ependymal cells)

Simple squamous epithelium

(Endothelium of capillary)

Ventricle

SIMPLE EPITHELIA

• Slide 85 Jejunum

Simple columnar epithelium

JEJUNUM

Wall of jejunum

Lumen of jejunum

Plica circulares (Plicae circulares – plural)

Villi (plural) Villus (singular)

Lumen

JEJUNUM

PLICA CIRCULARESwith a core of connective tissue - submucosa

Submucosa

Villus

Simple columnar

epithelium

Lumen

VILLUSwith a core of connective tissue – lamina propria

Lamina propria

Goblet cell

Columnar cell

Microvillus (striated) boarder

Lumen

SIMPLE EPITHELIA

• Slide 32 Trachea and Oesophagus

Trachea - Pseudostratified ciliated columnar epithelium with goblet cells

TRACHEA AND OESOPHAGUS

Trachea

Oesophagus

C shaped hyaline

cartilage ring

Folded oesophagealepithelium

Lumen

Lumen

EpitheliumCartilage

Glands in the submucosa

TRACHEA

Epithelium

Lumen

Submucosa with a hyaline cartilage Lamina propria

Muscularis mucosa

Submucosal glandsTRACHEA

Goblet cell

Cilia

Pseudostratified ciliated columnar epithelium with goblet cells

Basement membrane

Columnar cell

Note how nuclei of different cells lay on different levels within this simple epithelium, giving the false stratified appearance (hence the name)

Lumen

TRACHEA

STRATIFIED EPITHELIA

• Slide 32 Trachea and Oesophagus

Oesophagus – Stratified squamous non-keratinized epithelium

TRACHEA AND OESOPHAGUS

Lumen

Epithelium

OESOPHAGUS

Lumen

StratifiedEpithelium

Lamina propria

Muscularis mucosa

Muscularis externa

Submucosa

Stratified squamous non keratinized epithelium

Note: Black arrows are pointing at the nuclei present within the uppermost layer of squamous epithelial cells

Note: Multiple layers of epithelial cells changing the shape from the basement membrane towards the lumen of the organ

Lumen

OESOPHAGUS

Note: Black arrows pointing at the nuclei present within the uppermost layer of squamous epithelial cells

“Islands” of connective tissue within epithelium

Lumen

OESOPHAGUS

STRATIFIED EPITHELIA

• Slide 35 Thick skin

Stratified squamous keratinized epithelium

THICK SKIN

Epidermis

Dermis

Hypodermis

Free surface

Epidermis

Dermis

Hypodermis

Epidermal ridgeDermal papilla

Free surface

THICK SKIN

Stratified squamous keratinized epithelium

Numerous layers of keratinized epithelial cells which will eventually peel off

“Islands” of connective tissuewithin epidermis

THICK SKIN

Stratified squamous keratinized epithelium

Note: The change in the cell shape from the cuboidal , nucleated cells laying on the basement membrane to the squamous keratinized cells in the uppermost layers

Clear cell

THICK SKIN

STRATIFIED EPITHELIA

• Slide 43 Urinary bladder

Transitional epithelium (Urothelium)

URINARY BLADDER

Note the folded epithelium of the urinary bladderin the relaxed state

Smooth muscle

SerosaMucosa

Lum

en

Note: Mucosa consists of epithelium (urothelium) and connective tissue – lamina propria

Lum

en

Urothelium

Lamina propria

Smooth muscleMucosa

URINARY BLADDER

Lumen

Urothelium

UrotheliumUmbrella shaped cells, some binucleated

Lamina propria

Note: The number of cell layers (6-8) in the relaxed state of this stratified epithelium will decrease (3-4) when the bladder fills up with urine. Dome shaped umbrella cells will become flattened

URINARY BLADDER

Lumen

Umbrella shaped cells

Note: Umbrella cells are large, elliptical often binucleated cells with prominent nucleoli, vacuolated cytoplasm and apical plaques containing uroplakins. They cover multiple underlying transitional cells in a parasol-like fashion. Intermediate cells are cuboidal to low columnar while basal cells are more cylindrical, can be flat when bladder wall is stretched and lie on continuous basement membrane.

Vacuolated cytoplasm

Apical plaquesIntermediate cells

Basal cells