Epithelial tissue

1. Epithelial
tissue
By
Dr. Jamal Ahmad Khan

2. •Epithelial tissue are present in layers.
Lower most layer rests upon basement
membrane and upper most layer is is free.
•The cells are very close to each other and
are joined together by tight junction,
desmosomes, and gap junction.
•Upper most layer is towards either
external surface of body or towards lumen
of any cavity or tubes.

3. • Classification of epithelial
tissue
•1) Simple epithelium
•, 2) Compound or Stratified
epithelium
•3) Psuedostratified epithelium
•4)Transitional epithelium
•5) Glandular epithelium

5. •Simple epithelium
• These epithelium have cells arranged in single layer
resting on basement membrane.
• The free surface is facing towards lumen of cavities
or glands.
• According to shape of cell simple epithelium are of
following types
• 1) Squamous simple epithelium
• The cells are flat polygonal with bulging nucleus.
• Cells are attached to each other like tiles.
• These tissues are present in wall of blood capillaries and
alveoli of lungs.

6. •Cuboidal simple epithelium
• The cells are cubical in shapes and present in
single layer.
• These are found in ducts of glands and tubular
part of nephron.
• Functions of these tissue is secretion and
absorption.
•Columnar simple epithelium
•The cells are elongated pillar like arranged in
single layer. The nucleus is elongated and
present towards base.
•The free surface protoplasmic outgrowth

7. Cillated simple
epithelium
The cells may be cuboidal or columnar
have cillia on their free surface .
These tissue sre present in respiratory
broncheoles and fallopian tube.
The cilliary movement of these tissue
push the fluid or material in a
particular direction.

8. •Compound or Stratified epithelium
• The cells are present in many layers. Lower most
layer rests on basement membrane and upper
most layer is free facing towards external
environment or lumen of cavity or tube.
• According to these may be :-
•Squoumous stratified
•Cuboidal stratified
•Clomnar stratified

10. •Squomous epithelium may have
upper most layer with keratin
deposited dead cells called
Keratinized epithelium. Presrent in
epidermis of skin. Function is
protection.
•Squomous epithelium not having
keratinized uppermost layer are
called nonkeratinized epithelium .
Present in buccal cavity, lips,
undersurfsce of tongue, upper

11. •Cuboidal stratified epithelium are
present in sweat glands, mammary
gland and salivary gland.
•Function is protection.
•Clumnar stratified epithelium are
present in male urethera and ducts
of some glands
•Function is protection and secretion.

12. •Psuedostratified epithelium
• Cells are present in single layer All cells present on
basement membrane but few cellscdonot reach the
free surface so appear as multilayered.
• Free surface is cilliated. Present in respiratory
passage and cillia work as escaltor for mucus and
these also secrete mucus.
•Transitional epithelium
• The multilayered cells may be cuboidal or
columnar in relax condition but become flat on
stretching. Present in urinnary bladder ureter
and urethera.

13. •Glandular epithelium
• Some epithelial cells are modefied and their function is
secretion of some substances.
• On the basis of mode of secretion these may be following
types
• MEROCRINE
• The upper end of cells release the secretion and cells
remain unchanged. e. g. sweat glands, salivary gland and
tear gland
• APOCRINE
• The upper end of cell sepperated out on maturation with
releasing substances. e. g. mammary gland
• HOLOCRINE
• The whole cell on maturation become dead havin
secretions. e. g. Sebacious gland and Meibomian gland.

15. • On the basis of structure the glandular epithelium are
following types:-
• Simple tubular eg intestinal glands
• Simple coiled eg sweat glands
• Simple branched tubular eg gastric glands , mucous
glands of oesophagus tongue and deudenum
• Simple Alveolar a stage of simple branched
• Simple branched Alveolar eg sebaceous gland
• Compound tubular eg mucus gland in mouth,
bulbourertheral gland and testese
• Compound Alveolar eg mammary gland
• Compound tubuloalveolar eg salivary gland, glands of
respiratory passage and pancrease.

17. •On the basis of transport to target of
secretion,the glands may be exocrine or
endocrine.
•Exocrine glands sends their secretion to
target by ducts . eg Salivary glands, Sweat
glands.
•Endocrine glandssend their
secretion to target by releasing them
in blood. eg Pitutary gland.