Epithelial tissue
Dr. Amam Ali Amam
PhD: Periodontal Disease
The human body is composed of only
4 basic types of tissue
Epithelial
tissue
Connective
tissue
Muscular
tissue
Nervous
tissue
They are formed by:
Cells
Molecules
of the extracellular matrix
The main characteristics of these basic types
of tissue:
tissue
Cells
Extracellular
matrix
Main
Function
Nervous
Intertwining
None
elongated processes
Transmission of
nervous impulses
Epithelial
Aggregated
polyhedral cells
Very small amount
Lining of surface or
body cavities,
glandular secretion
Muscle
Elongated
contractile cells
Moderate amount
Movement
Connective
Several types of
fixed and
wandering cells
Abundant amount
Support and
protection
Connective Tissue
is characterized by:
The abundance of extracellular
material produced by its cells.
Muscular Tissue
is composed of:
elongated cells that have the
Specialized function of contraction .
Nervous Tissue
is composed of:
cells with elongated processes
that receive, generate and
transmit nerve impulses
Epithelial Tissues
are composed of:
closely aggregated
very little
Polyhedral Cells
Extracellular Substance
Epithelial tissue:
These tissues exist not as isolated units but rather
is association with one another and in variable
proportions, forming different organs & systems
of the body.
Epithelial cells covers or line surfaces
of the body & cavities
(eg, skin, stomach, oral cavity, all tubes inside the blood vessels).
The principal Functions of Epithelial tissues are:
1- Covering & lining of surfaces (eg, skin, intestines).
2- Absorption (eg, intestines).
3- Secretion (eg, glands).
4- Sensation (eg, gustative & olfactory neuroepithelium)
5- Contractility (eg, myoepithelial cells)
Epithelial Cells are covering & lining surfaces
and cavities of the body (external & internal surfaces).
Therefore, everything that enter or leave the body
should cross the epithelial sheet.
Relationship between Epithelial Cells (E.C).
It’s very strong (firm), they should be continuous
Because they are going to ( cover, protect, make the function)
as perfect as possible.
They communicate because they want to know the
function of the other, and to live ( if one cell is underworking
then the other cell should raise up their level to cover for it )
or if it died.
Most organs can be divided into 2 components
1- Parenchyma
It’s composed of the
cells responsible for
the main functions
typical of the organ
2- Stroma
It’s the supporting
tissue, it’s made of
connective tissue,
except in the brain
and spinal cord
Forms of Nucleus & it’s location
Epithelial Cell nuclei have distinctive shapes:
Epithelial Cell
Nucleus shapes
Location
Cuboidal
Squamous
Spherical
Flattened
Central
Central
Columnar
Oval
near the
Basal
The long axis of the nucleus is always parallel
to the main axis of the cell.
Specialization of the cell surface
1- Microvilli.
2- Cilia.
3- Flagella.
1- Microvilli
They are found mainly on:
1- the Free cell surface.
2- absorptive cells (lining epithelium of the small intestines
& the cells of the proximal renal tubule).
Microvilli
2- Cilia
They are cylindrical motile
structures on the surface
of some epithelium cells.
2 Types of Epithelium
according to structure & function
2- Glandular
Epithelium
1- Covering
Epithelium
1-Simple
1-Squamous.
2-Cuboidal.
3-Columnar.
2-Stratified
3- Pseudostratified
1-Squamous keratinized.
2-Squamous non-keratinized
3-Cuboidal.
4-Transitional.
5-Columnar.
Types of covering epithelium
1-Simple
2-Stratified
3- Pseudostratified
Types of covering epithelium
Simple Epithelium Patterns
1-Squamous.
2-Cuboidal.
3-Columnar.
1- Simple Squamous Epithelium
1- Simple Squamous Epithelium
Where it’s Located ?
 lungs (alveoli).
 capillary ((endothelium).
 lining of pleural cavity, the
pericardium, and the peritoneum.
 Bowman's capsule (Kidney).
 Blood vessels ((endothelium).
2-Simple Cuboidal Epithelium.
2- Simple Cuboidal Epithelium
2- Simple Cuboidal Epithelium
Where it’s Located ?








follicle of thyroid gland
collecting ducts of kidney
salivary glands.
Pancreas.
Ovary.
Uterus.
Lining of intestine.
gallbladder
Types of covering epithelium
3-Simple Columnar Epithelium.
3- Simple Columnar Epithelium
3- Simple Columnar Epithelium
Where it’s Located ?
 Gallbladder.
 surface epithelium of stomach.
 Uterine glands (all phases).
 small intestine
Types of covering epithelium
Type
Cell
Form
Examples of
Distribution
Squamous Lining of vessels
(endothelium).
Serous lining of
cavities; pericardium,
pleura, peritoneum
(mesothelium)
Simpl
e
Cuboidal
Covering the ovary,
thyroid.
Columnar Lining of intestine,
gallbladder.
Main Function
Facilitates the movement of
the viscera (mesothelium),
active transport by pinocytosis
(mesothelium & endothelium),
secretion of biologically active
molecules (mesothelium)
Covering, secretion.
Protection, lubrication,
absorption, secretion.
Types of covering epithelium
1-Simple
2-Stratified
3- Pseudostratified
Types of covering epithelium
Stratified Epithelium Patterns
1-Squamous keratinized.
2-Squamous non-keratinized
3-Cuboidal.
4- Transitional.
5-Columnar.
Stratified Squamous keratinized Epithelium
Stratified Squamous non-keratinized (moist)
Stratified Squamous non-keratinized (moist)
Where it’s Located ?





oral mucosa
pharynx
esophagus
anal canal
uterine cervix & vagina
Squamous Stratified Epithelium
Transitional Stratified Epithelium
Where it’s Located ?
Bladder, Ureters, renal calyces.
Transitional Stratified Epithelium
Cuboidal Stratified Epithelium
Where it’s Located ?


Ducts of sweat glands,
developing ovarian follicles.
Types of covering epithelium
Type
Cell Form
Surface layer squamous
keratinized (dry).
Examples of
Distribution
Main Function
Epidermis.
Protection ; prevents
water loss.
Mouth,esophagus,
larynx, vagina,
anal canal
Protection, secretion;
prevents water loss.
Cuboidal
Sweat glands,
developing
ovarian follicles.
Protection, secretion.
Transitional: domelike to
flattened, depending on
the organ.
Bladder, Ureters,
renal calyces.
Protection,
distensibility.
Columnar.
Conjunctiva.
Protection.
Surface layer squamous
Stratified nonkeratinized (moist).
Ciliated Pseudostratified Epithelium
Maxillary Sinus
Pseudostratified columnar Epithelium
Trachea
Common types of covering epithelia in the human body
Type
Simple
Pseudostratified
Stratified
Cell Form
Examples of
Distribution
Main Function
Squamous
Lining of vessels (endothelium).
Serous lining of cavities; pericardium,
pleura, peritoneum (mesothelium)
Facilitates the movement of the
viscera (mesothelium), active
transport by pinocytosis
(mesothelium & endothelium),
secretion of biologically active
molecules (mesothelium)
Cuboidal
Covering the ovary, thyroid.
Covering, secretion.
Columnar
Lining of intestine, gallbladder.
Protection, lubrication,
absorption, secretion.
Some columnar
& some cuboidal.
Lining of trachea, bronchi, nasal cavity.
Protection, secretion; ciliamediated transport of particles
trapped in mucus.
Surface layer squamous
keratinized (dry).
Epidermis.
Protection ; prevents water loss.
Surface layer squamous
nonkeratinized (moist).
Mouth, esophagus, larynx, vagina,
anal canal
Protection, secretion; prevents
water loss.
Cuboidal
Sweat glands, developing ovarian
follicles.
Protection, secretion.
Transitional: domelike to
flattened, depending on
the organ.
Bladder, Ureters, renal calyces.
Protection, distensibility.
Columnar.
Conjunctiva.
Protection.
Glandular Epithelium

1.
2.
3.
Glandular epithelial cells (store &
secrete :
proteins (eg: pancreas)
lipids, ( egsebaceous glands)
carbohydrates and proteins,
(eg: salivary glands)
•
•
Mammary glands do all that.
Secretes substances from the blood,
sweat glands
Types of glands


1.
2.
Unicellular: goblet glands.
Multicellular:
Exocrine
Endocrine
Glandular Epithelium