epithelium histology

1. Epithelium
Dr. Maria Shahzad
Dept: Anatomy
Histology practical online class
Date:4th may 2020

2. (stratified or multilaminar )

4. Epithelium is collection of closely apposed cells
with very small amount of extracellular matrix .
A. Simple epithelia (unilaminar)
1. Simple squamous epithelium
2. Simple cuboidal epithelium
3. Simple columnar epithelium
4. Pseudostratified epithelium

5. 1) Simple Squamous Epithelium
• A single layer of thin flat cells
• Roughly polygonal in shape
• Flattened nucleus located in center
• Examples;
1) endothelium which covers the
internal surface of heart, bloodvessles
and lymph vessles.
2) mesothelium which lines the
pericardial, pleural and peritoneal
cavities.
3) the lining epithelium of the alveoli of
lung .

6. 2)Simple cuboidal epithelium
• Single layered roughly square
shape
• Spherical nucleus located in
center
• Examples;
1) Intercalated ducts of salivary
glands and pancreas.
2) The distal convoluted tubules of
kidney
3) Outer surface of ovary
4) Respiratory bronchioles

7. 3)Simple columnar epithelium
• A single layer of column-shaped
cells
• Nucleus is oval in shape and
located near the base of the cell
• In many locations in the body ,
the cells show modifications on
their apical surface, which
includes microvilli , kinocilia and
sterocilia
• Examples;
1) Lines internal surface of stomach
, intestine ,gallbladder and uterus .

8. 4)Pseudostratified epithelium
• Modification of simple columnar
epithelium in which nuclei of cells
lie at different levels
• All cells rests on basement
membrane but all donot extend to
free surface so appear as ; Tall
columnar cells and basal cells .
• The nuclei are present in wider
part so , are found aligned at two
or more levels in epithelium
creating false appearance of cell
stratifications histologically.
• Shows modifications on their apical
surface as cilia or sterocilia .
• Examples;
1) Lines nose, nasopharynx, trachea,
bronchi
2) Male genital ducts

9. Stratified (multilaminar) Epithelia
1. Stratified squamous epithelium
2. Stratified cuboidal epithelium
3. Stratified columnar epithelium
4. Transitional epithelium ( Urothelium )

10. 1)Stratified squamous epithelium
• Lines those surfaces which are subjected
to wear and tear.
• Basal layer ; ( divide mitotically)
Low columnar or cuboidal cells
• Next to basal layer ;
few larger polygonal cells
• Surface layer;
cells gradually become flattened and at
surface they are squamous.
• Two types ;
1) Keratinized (cornified)
e.g epidermis
2) Non keratinized (non cornified)
e.g lines oral cavity ,oropharynx,
esophagus and vagina

11. 2)Stratified cuboidal epithelium
• Consists of two or three layers of
cuboidal cells
• Present only as lining of larger
ducts of some endocrine glands
(pancreas and salivary glands)
• Lines ducts of sweat glands
• Provides stronger lining only , no
absorptive or secretory activity

12. 3)Stratified columnar epithelium
• Consists of columnar cells rests on
one or more layers of roughly
cuboidal cells .
• Not common
• Examples;
1) Line some parts of male urethra
2) Conjunctiva of eye

13. 4)Transitinal epithelium (urothelium)
• Special type lining the urinary tract
• Designed to withstand stretch produced by
distention of urinarypassage
• Prevent reabsorption of urine
• Lines renal calyces,renal pelvis,ureters,urinary
bladder,and proximal parts of male and female
urethra
• Two forms;
1) Undistended(contracted) urinary bladder;
consists of 6 or 8 cell layers , basal layer
contain cuboidal cells ,over basal layer several
polygonal cells ,superficial layer consists of dome-
shaped cells and and some cells contain two nuclei.
2) Distended (stretched) urinary bladder;
consists 2 or 3 layers ,basal layer low
cuboidal cells over which 2 or 3 layers of large flat
cells present .

14. Refrences;
• Medical Histology (Laiq Hussain Siddiqui)
• diFiore's Atlas of Histology

15. Thank you