Histology:
Epithelial tissue
Epithelial Tissue is presented in two forms:
1. Covering Epithelia:
2. Glandular Epithelia:
1. Simple Epithelium: contain only one layer of cells.
2. Stratified Epithelium: contain more than one layer.
Simple Epithelium is classified according to the
morphology of the cell into:
1. Simple Squamous Epithelium
2. Simple Cuboidal Epithelium
3. Simple Columnar Epithelium
4. Pseudo stratified Epithelium
2. Stratified Epithelium: contain more than one
layer.
Stratified Epithelium is classified according to the
morphology of the cell into:
Stratified squamous epithelium
Stratified cuboidal epithelium
Stratified columnar epithelium
Transitional epithelium/ Urothelium
2. Glandular Epithelia:
exocrine
II) endocrine
III) Classification
I)
Stratified Squamous Epithelium
(Non keratinized(
Stratified epithelium is named for the shape of the cells 
forming the outermost layers. Stratified squamous
epithelium consists of many layers of cells, making this
tissue relatively thick. Cells nearest the free surface are
flattened the most, whereas those in the deeper layers,
where cell division occurs, are cuboidal or columnar.
As the newer cells grow, older ones are pushed farther
and farther outward, where they flatten
Stratified squamous epithelium lines the oral cavity, 
esophagus, vagina, and anal canal. In these parts, the
tissue is not keratinized; it stays soft and moist, and the
cells on its free surfaces remain alive.
H&E stain of biopsy of normal esophagus showing
the stratified squamous cell
12
2-Stratified Squamous (keratinized)
Epithelium
Stratified Squamous (keratinized) Epithelium is similar 
to stratified squamous (Non keratinized) Epithelium
except that the superficial layers are composed of dead
cells whose nuclei and cytoplasm have been replaced
with keratin. (epidermis of skin).
14
The outermost layer of the skin (epidermis) is 
stratified squamous epithelium. As the older cells are
pushed outward, they accumulate a protein called
keratin, then harden and die. This “keratinization”
produces a covering of dry, tough, protective material
that prevents water and other substances from
escaping from underlying tissues and blocks chemicals
and microorganisms from entering.
the stratified squamous cell epithelium squamous epithelial
surface, referred to as the epidermis. The layer of keratin here is
named the stratum corneum
Stratified Squamous (keratinized)
17
3-Stratified Cuboidal Epithelium
Stratified cuboidal epithelium which contains multiple 
layers of cuboidal cells, lines the ducts of sweat glands.
19
3-Stratified Cuboidal Epithelium 
20
4-Stratified Columnar Epithelium
It's composed of more than one layer of cells and the
superficial layer is columnar in shape. This epithelium is
found only in a few places of the body,
Stratified Columnar
Epithelium
Urinary Epithelium
Epithelial type is urinary epithelium 
Unlike pseudo stratified epithelium , this is a 
true stratified form . As the name implies ,
it's found only in the urinary tract. This
image is from the urinary bladder, which is
lined with it.
 Notice that the cells in the deep layers are
cuboidal to columnar; that those of the
topmost layer are larger, pale and washed out
looking, with small nuclei; and that the
border is "scalloped." These are the definitive
characteristics of this epithelial type
The urinary bladder has to expand and contract
as the amount of stored urine increases or decreases.
The epithelium you see here is in a bladder that's
contracted (because it's empty).To accommodate this
change in organ volume, the lining epithelium has to
have extra membrane so that when the bladder is
distended , the cells aren't stretched
and torn .