Histology

1. EPILTHELIUM
Dr. Rabia Inam Gandapore
Assistant Professor
Head of Department Anatomy
(Dentistry-BKCD)
B.D.S (SBDC), M.Phil. Anatomy (KMU),
Dip. Implant (Sharjah, Bangkok, ACHERS) , CHPE
(KMU),CHR (KMU), Dip. Arts (Florence, Italy)

2. Teaching Methodology
 LGF (Long Group Format)
 SGF (Short Group Format)
 LGD (Long Group Discussion, Interactive discussion with the use of models or diagrams)
 SGD (Short Group)
 SDL (Self-Directed Learning)
 DSL (Directed-Self Learning)
 PBL (Problem- Based Learning)
 Online Teaching Method
 Role Play
 Demonstrations
 Laboratory
 Museum
 Library (Computed Assisted Learning or E-Learning)
 Assignments
 Video tutorial method

3. Goal/Aim (main objective)
 To help/facilitate/augment the students about the:
1. Define tissue
2. Describe the basic tissues in human body
3. Define epithelium
4. Classify epithelium
5. Describe the general features of epithelium
6. Explain the specialized functions of different types of epithelial cells
7. Describe the structure of main types of cell junctions.

4. Specific Learning Objectives (cognitive)
At the end of the lecture the student will able to:
 Recognize the histological features of the types of Epithelium
 Sketch labeled diagram of the different types of Epithelium

5. Psychomotor Objective: (Guided response)
 A student to draw labelled diagram of different types of epithelium with at least 3
differentiating points

6. Affective domain
 To be able to display a good code of conduct and moral values in the class.
 To cooperate with the teacher and in groups with the colleagues.
 To demonstrate a responsible behavior in the class and be punctual, regular, attentive and
on time in the class.
 To be able to perform well in the class under the guidance and supervision of the teacher.
 Study the topic before entering the class.
 Discuss among colleagues the topic under discussion in SGDs.
 Participate in group activities and museum classes and follow the rules.
 Volunteer to participate in psychomotor activities.
 Listen to the teacher's instructions carefully and follow the guidelines.
 Ask questions in the class by raising hand and avoid creating a disturbance.
 To be able to submit all assignments on time and get your sketch logbooks checked.

7. Lesson contents
Clinical chair side question: Students will be asked if they know what is the function of
Outline:
 Activity 1 The facilitator will explain the student's types of epithelium
 Activity 2 The facilitator will ask the students to make a labeled diagram of the different types of
epithelium with at least 3 differentiating points.
 Activity 3 The facilitator will ask the students a few Multiple Choice Questions related to it with
flashcards.

8.  Students assessment: MCQs, Flashcards, Diagrams labeling.
 Learning resources: Langman’s T.W. Sadler, Laiq Hussain Siddiqui, Snell Clinical Anatomy, Netter’s
Atlas, BD Chaurasia’s Human anatomy, Internet sources links.

9. Tissues
 An organized aggregation of cells or
groups of cells that function in a
coordinated manner to perform one or
more specific functions.
 Tissues combine to form larger functional
units, called ORGANS.
 Its basic functional units responsible for
maintaining body functions.

10.  Human have 4 basic tissues that makeup body
1. Epithelium
2. Connective Tissue
3. Muscular Tissue
4. Neuronal or Nervous Tissue
5. Blood

11. Epithelium
 TYPES
 CLASSIFICATION

12. Epithelium
 Is Specialized tissue which are a cohesive sheet of cells that are ;
A. Made up of tightly apposed cells (very close)
B. Avascular sheets
C. Capable of renewal & regeneration.
1. Non-specialized epithelium - all cells
2. Specialized epithelium - stem cells
D. Epithelium Types
1. Simple
2. Stratified (pseudostratified)

14. E. Structurally & functionally polarized: Have
apical, lateral & basal domains
 Apical cell surface specializations: Shape of cells
& structural specializations of the free (apical)
cell surface, depends on tissue function(s).
1. Microvilli - actin filaments
2. Cilia - microtubules (dyneins)
F. Covers the external surface & lines internal
surface of body. Arranged in 2 fashion,
1. Membranous Epithelium
2. Glandular Epithelium

16. 1. Membranous Epithelium; Long sheets of cells,
 a. Covering external surface of body
- Dermis
 b. Lines internal closed cavities
- Cardiovascular system
- Peritoneal cavity
- Pleural cavity
- Pericardial cavity
 c. Epithelium lines all body tubes which communicates to external
environment
- Respiratory Tubes
- GIT tubes
- UGS tubes

17. 2. Glandular tissue; Forms secretory
glands. Groupings of cells specialized
for secretion
a. Exocrine (ducts) gland
b. Endocrine (ductless) gland
 Secretion process by which small
molecules are taken up &
transformed, by intracellular
biosynthesis, into a more complex
product that is then actively
released from the cell.

22. G. Intercellular junctions: Are held together by intercellular
junctions & bind to underlying connective tissue via
basement membrane (LM) or basal lamina (EM).
1. Zonula occludens (tight junction) - ridges & grooves,
seal intercellular spaces - Selective permeability barrier
2. Zonula adherens - actin filaments - cell to cell adhesion
3. Macula adherens (desmosome) - intermediate filaments-
attachment plaque (spot)
4. Hemidesmosome - attaches epithelium to basal lamina
5. Nexus (gap junction) - connexons - cell to cell
communication

23. Basis of Classification
1. Shape of Cells
a. Flat / Spindle
b. Cube
c. Column
d. Pseudo
2. Width, Height and Depth
a. Columnar (Height more)
b. Cuboidal (Equal)
c. Squamous (flat, width more)
d. Transitional (Mixed)
3. Location/ Position of Nuclei
a. Towards base (Columnar epithelium)
b. Centrally located
c. Peripherally located
4. Layers of Epithelial cells
a. Single layer= Simple epithelium
b. Multiple layer= Stratified epithelium

24. Classification of Epithelium

25. Classification of Epithelium
1. Simple Epithelium (Single Layer)
a. Simple Squamous
b. Simple Cuboidal
c. Simple Columnar
d. Pseudo-Stratified
2. Stratified Epithelium (Multiple Layer)
a. Stratified Squamous
-Keratinized/ coinified
-Non-Keratinized
b. Stratified Cuboidal
c. Stratified Columnar
d. Stratified Transitional
-Distended (Less layers)
-Non-Distended (More layers)

27. Function of Epithelium

28. Functions
 Protection: (Abrasion/ Injury) e.g. Skin (Epidermis)
 Secretion: from epithelial cells e.g. GIT tube
 Absorption: e.g. proteins broken into amino acids
 Sensory: e.g. olfactory epithelium (Smell), Tongue
epithelium (Gustatory), Ear Epithelium (hearing/Balance),
Eye Epithelium (Vision)
 Transport: O2, Co2

29. Simple Epithelium
SIMPLE SQUAMOUS
SIMPLE CUBOIDAL
SIMPLE COLUMNAR
PSEUDO-STRATIFIED (RESPIRATORY)

30. 1. Simple Squamous Epithelium
 Morphology:
 Thinnest layer, Single layer (egg shaped)
 Flat cells on basement membrane
 Central flat and elongated nucleus
 Height small, Width large
 Cytoplasm cannot be seen (because of flat
nucleus)
 Functions
 Absorption
 Transportation of material
 Diffusion ,Osmosis
 Filtration
 Shedding
 Location
 Cardiovascular system (Endothelium)
 Blood System (Endothelium)
 Respiratory system (Alveoli)
 Kidney tubules
 Lymphatic vessels (endothelium)
 Wall of intestinal (Vessels)
 Mesentery (Mesothelium)
 Sub mucosal layer of vessels

33. 2. Simple Cuboidal Epithelium
 Morphology:
 Single layer cells on basement membrane
 Cube shape: Equal height ,width, depth
 Nuclei central and round
 Function
 Secretion
 Reabsorption
 Location
 Surface of ovaries
 Nephron kidney (Collecting tubules, proximal convoluted tubules)
 Glandular Ducts (Salivary, thyroid follicles)

35. 3. Simple Columnar Epithelium
 Morphology
 Single layer
 Tall cells/ column, Height= Large, Width=
Small
 Nuclei towards basement membrane
 Goblet cells (Mucin production)
 Finger like projections (Microvilli or cilia)
 Function
 Secretion: Microvilli secrete digestive
enzymes to absorb digested food
 Absorption: Cilia ,mucus production
 Protection
 Location
 Small intestine (Goblet cells, microvilli)
 Gall bladder (No Goblet cells)
 Large intestine (Goblet cells)
 Gastro intestinal system
 Stomach (Colon), villi absent
 Vas deferens (Stereocilia)
 Respiratory tract (Pseudo-stratification)
 Fillopian tube (Surface cilia)

40. 4. Pseudo-Stratified Epithelium (Respiratory)
 Morphology
 Single layer cells on basement membrane
 Appears stratified i.e. oval & elongated nuclei at different
levels
 Tall & Short Cells lie on basement membrane
 Ciliated or non-ciliated
 Goblet cells
 Function
 Secretion
 Removal of foreign body
 Location
 Epididymis/Male
 Trachea
 Esophagus
 Fallopian tube

48. Stratified Epithelium
1. STRATIFIED SQUAMOUS
a. KERATINIZED (CORNIFIED)
b. NON-KERATINIZED (CORNIFIED)
2. STRATIFIED CUBOIDAL
3. STRATIFIED COLUMNAR
4. STRATIFIED TRANSITIONAL
a. DINSTENDED
b. UN-DISTENDED

49. 1. Stratified Squamous Epithelium
A. Keratinized (Cornified) Stratified Squamous Epithelium
 Morphology
 Multiple layer (Stratified) = scuff off (Mitotic division)
 Lower layer cells rest on basement membrane (Cuboidal/columnar) while rest cells donot
 Upper cell flat , squamous & NO nuclei
 Keratin abundant
 Spinous cells (Site where desmosomes, macula adherens attach cell to one another)
 Function
 Protection against wear & tear: Abrasion
 Waterproof to reduce evaporation
 Location
 Skin
 Esophagus
 Sole of feet

64. B. Non-Keratinized (Cornified) Stratified Squamous
Epithelium
 Morphology
 Multiple layer (Fish scales type) : Polyhedral cells/
Cuboidal/ Columnar
 Lower cell rest on basement membrane
 Uppermost squamous but has nuclei all over
 No keratin
 Function
 Mucus secretion/ Moist/lubrication
 Protection, abrasion
 Location
 Vagina
 Mucosa of oral cavity (upper esophagus)
 Trachea
 Foreskin
 Internal portion of lips
 Anal canal
 Ecto-cervix

66. 2. Stratified Columnar Epithelium
 Morphology
 Multiple layer
 Tall cell/ Columnar, Height=Large, Width= Small
 Nuclei elongated towards base
 Goblet cells (Mucin)
 Function
 Protection
 Mucous secretion
 Location
 Large ducts of glands
 Conjunctiva of eye
 Part of Pharynx
 Anus
 Uterus
 Male urethra/ Vas deferens

67. 3. Stratified Cuboidal Epithelium
 Morphology
 Multiple layer (stratified)
 Cube shape cells on basement membrane,
Equal height width & depth
 Nuclei central & round
 Function
 Absorption
 Secretion
 Excretion
 Location
 Ducts of same gland (Salivary gland , sweat
gland)
 Kidney tubules

70. 4. Stratified Transitional Epithelium
 Cells (Squamous + cuboidal)
 Morphology
a. Distended (Stretched)= Less layer, cells slide over
each other, surface cell squamous & flattened
b. Non Distended (not stretched)= Many layers.
Umbrella cells/ Dome shaped bulge out inside lumen &
cells has plaque on surface
 Function
 Adapted to extensibility
 Water impermeability (Bladder fills with urine)
 Protection from toxins (Urine)
 Location
 Urinary tract ; Ureter, bladder, urethra

74. Thank You
ANY QUESTIONS?