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CELLS AND TISSUES (CAT 2114)
Laboratory No. 4
Topic: Histology of Epithelium & Glands
Faculty:Dr VENNILA VIJAYA SREE
MBBS;MASTERS in pathology(MD)
OBJECTIVES:
-Histology of Epithelium
1. Identify and describe the characteristics of epithelial tissues.
2. Identify and describe the types of epithelial tissues based on histological
characteristics, organ source and correlate with the functions.
- Histology of Glands
3. Identify and describe the types of glands based on histological characteristics, organ
Source and correlate with the functions.
At the end of the practical session, the students should be able to:
1. Classify epithelium.2. Describe characteristic features of each epithelium3. Describe functions of each epithelium.4. Able to give examples for each epithelium.5. Describe the types of glands6. Able to give examples of glands
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Slides needed for this activity are:
1. Scalp2. Skin3. Trachea4. Finger nail5. Oesophagus6. Stomach7. Duodenum8. Colon9. Sublingual gland10.Parotid gland11.Submandibular gland12.Thyroid gland13.Mammary gland14.Liver & Gall Bladder15.Pancreas16.Kidney17.Urinary Bladder18.Epididymis19.Uterine Tube
INTRODUCTION TO THE HISTOLOGY OF EPITHELIUM
1. Definition: Outer surface of the body and the luminal surfaces of cavities within the bodyare lined by one are more layers of cells that completely cover them. such layers are
called epithelia
2. Epithelia also covers ducts and secretory elements of glands.3. Little or no intercellular substance.4. Cell junctions are present.5. All cells in the basal layer rest on the basement membrane.6.
Avascular-Diffusion from capillaries in the underlying connective tissues.
7. Regeneration-Continuous wear and tear.
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Types of epithelium: Structurally and functionally divided into:
1. Covering epithelium, 2. Glandular epithelium. Covering epithelium
- covers the body surfaces or lines the cavities of the body-external surface-epidermis of the skin
-internal surface-Body cavities (peritoneal cavity, pericardial cavity and pleural
cavity)
-tracts/tubes(digestive tract, respiratory tract).
Glandular epithelium-Specialised cells that produce secretion.
CLASSIFICATION OF COVERING EPITHELIAI). NUMBER OF CELL LAYERS
-SIMPLE
Contains only 1 layer of cells( almost always found at interfaces involve in
selective diffusion, absorption or secretion)
-STRATIFIED
-contains more than 1 layer of cells
-PSEUDOSTRATIFIED
II). SHAPE OF THE CELLS
-Squamous, cuboidal, columnar
III). PRESENCE OF SURFACE SPECIALIZATIONS
-Cilia, Keartin
SIMPLE EPITHELIA
Formed by a single layer of cells- Simple squamous epithelium- Simple cuboidal epithelium- Simple columnar epithelium- Pseudostratified epithelium
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ACTIVITY 1:SIMPLE SQUAMOUS EPITHELIUM
Instruction: Examine the slide of lung alveoli & Capillaries
Observe Flattened cells with disc-shape nuclei. LOCATIONS
-lining surfaces involved in passive transport e.g. lungs & capillaries
-Forms delicate lining of pleural, pericardial and peritoneal cavities.
FUNCTIONS:-allows passage of materials by diffusion and filtration.
-secretes lubricating substances in body cavities.
Draw the diagram of Simple Squamous epithelium & label it.
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ACTIVITY 2: SIMPLE CUBOIDAL EPITHELIUM
INSTRUCTION: Examine the slide of Collecting Ducts of
Kidney/Pancreas/Salivary glands
OBSERVE
- Cuboidal in shape.
- Round nucleus in the centre
- Lines small ducts and tubules(excretory, secretary or absorptive functions)
FUNCTIONS-Absorption
-Secretion
Draw the diagram of Simple Cuboidal Epithelium & label it
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ACTIVITY 3: SIMPLE COLUMNAR EPITHELIUM
INSTRUCTION: Examine the slide of Intestine/Gall bladder/uterine tube
OBSERVE
Tall column-like cells Oval nuclei towards the base. Often found in highly
absorptive surface.
FUNCTIONS:-absorption
-secretion.
Draw the diagram of SimpleColumnar Epithelium & label it.
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ACTIVITY4: SIMPLE CILIATED COLUMNAR EPITHELIUM
INSTRUCTION: Examine the slide of uterine tube
OBSERVE
Presence of cilia. On simple columnar
epithelium.
Each cilium consists ofprojection of plasma membrane.
Beat wavelike manner FUNCTIONS:
-Move accumulated mucous in the bronchi-In the uterine tube movements of cilia help in the passage of ova towards
the uterus.
Draw the diagram of SimpleCiliated Columnar Epithelium & label it.
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ACTIVITY 5: PSEUDOSTRATIFIED EPITHELIUM
INSTRUCTION: Examine the slide of Respiratory
tract/Epididymis/Ductus deferens.
OBSERVE-Appears as more than one layer but only a single layer is present with all cells resting
on the basement membrane.
-Cells are tall and short with nuclei located at different levels.
FUNCTIONS:- Absorption
-Secretion.
Draw the diagram of Pseudostratified Epithelium & label it.
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STRATIFIED EPITHELIUM
INTRODUCTION TO STRATIFIED EPITHELIUM
Formed by more than twolayers of cells
FEATURES: Mainly protective functions Poorly suited for function and
secretions of absorption and secretions
Classified based on the surface
cells.
Basal layer usually cuboidal. TYPES:
Stratified SquamousEpithelium
Stratified CuboidalEpithelium
Transitional EpitheliumSTRATIFIED SQUAMOUS EPITHELIUM
2 types: 1.Keratinized, 2.Non-Keratinized
ACTIVITY 6: INSTRUCTION: Examine the slide of skin-Keratinized
OBSERVE
Transition from cuboidal basalto flattened .
Divide continuously Dead keratinized cells at
surface. FUNCTION: Protection-withstand physical
abrasion and resist chemical injury
Draw the diagram ofKeratinized squamous epithelium & label the layers
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ACTIVITY 7: INSTRUCTION: Examine the slide of Oesophagus-Non Keratinized
Squamous epithelium
OBSERVE Transition from cuboidal basal
to flattened .
Divide continuously Living nucleated cell on the
surface
No Keratinisation on upperlayers
FUNCTION:Kept moist by glandular secretions
Draw the diagram of Non-
keratinized Squamous epithelium & label it.
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ACTIVITY 8: STRATIFIED CUBOIDAL EPITHELIUM
INSTRUCTION: Examine the slide of salivary gland duct
OBSERVE-multilayered cuboidal cells
Locations: Ducts of sweatglands, mammary glands, and Salivary glands
Functions: Protection
Draw the diagram ofstratified Cuboidal Epithelium & label it
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ACTIVITY 9: TRANSITIONAL EPITHELIUM
INSTRUCTION: Examine the slide of Urinary Bladder
Observe: Four to five cell layers thick. The basal cells are roughly
cuboidal, the intermediate cells are polygonal and the surface cells (umbrella or
dome cellsU) are large and rounded and may contain two nuclei.
In the stretched state,transitional epithelium often appears only two or three cells thick (although the
actual number of layers remains constant) and the intermediate and surface layers
are extremely flattened.
Functions: Withstand toxicity of urine Allow great degree of
distention.
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Draw the diagram oftransitional epithelium & label it.
GLANDULAR EPITHELIUM
1. Definition of Gland: Someepithelial cells are specialized to perform a secretary function and present singly or in
groups, constitute glands.
2. Some glands areunicellular,eg: Goblet cells of intestine, and most glands are multicellular .
3. Multicellular glands are 2types(by presence of duct)
1.Exocrine :Duct present, pour their secretion on to epithelial surface.
-Depending on type of secretion-Mucinous,Serous, and Sero-mucinous
2.Endocrine :Duct absent, pour their secretions into blood.
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4. Depending on shape/architecture
1. simple tubular
2. simple alveolar
3.compound tubular
4. Compound alveolar
5. Compound tubulo-alveolar
ACTIVITY 10 : UNICELLULAR (MUCOUS) GLAND
INSTRUCTION: Examine the slide of epithelial lining of colon
OBSERVE- big peculiar shape goblet cells
with abundant pink cytoplasm located between the epithelial lining of colon FUNCTION
- Secrets mucous
Draw the diagram of Gobletcells between the epithelial lining of colon & label
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ACTIVITY 11 : SWEAT GLAND
{ Coiled tubular (sero-mucous)glands}
INSTRUCTION: Examine the slide of finger tip/scalp
OBSERVE- Ducts with two layers of
cuboidal epithelium
FUNCTION- Secrets sweat
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Draw the diagram of Sweatgland & label it
ACTIVITY 12 : SEBACEOUS GLAND
{Multicellular ( holocrine ) gland}
INSTRUCTON: Examine the slide of scalp and identify the Sebaceous gland
OBSERVE- Sebaceous gland near the hair
follicle
- At the basement, cells arecuboidal. other cells are enlarged
FUNCTION
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- Secrets sebum
Draw the diagram ofSebaceous gland & label it.
ACTIVITY 13 : SUBLINGUAL GLAND
{ Mucous ( Multicellular-acinar ) gland }
INSTRUCTION: Examine the slide of Sublingual gland
OBSERVE- Pale stained cuboidal cells
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FUNCTION- Secrets mucinous saliva
Draw the diagram of
Sublingual gland & label it.
ACTIVITY 14 : PAROTID GLAND
{ Multicellular ( Serous ) gland }
INSTRUCTION: Examine the slide of Parotid salivary gland
OBSERVE
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- Darkly stained cuboidal cells FUNCTION
- Secrets serous saliva
Draw the diagram of Parotidgland & label it.
ACTIVITY 15 : SUBMANDIBULAR GLAND
{ Multicellular ( Serous & Mucinous ) gland }
INSTRUCTION: Examine the slide of Submandibular salivary gland
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OBSERVE- Serous demilunes- Combination of serous and
mucinous acinar glands
FUNCTION- Secrets seromucinous saliva
Draw the diagram ofSubmandibular gland & label it.
ACTIVITY 16 : THYROID GLAND
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{ Multicellular-Endocrine gland }
INSTRUCTION: Examine the slide of Thyroid gland
OBSERVE-
Its follicles contain secretaryproduct
FUNCTION- Secrets Thyroid hormone
Draw the diagram of thyroidgland & label it.
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ACTIVITY 17 : PANCREAS
{ Multicellular-Mixed ( Exocrine & Endocrine ) gland }
INSTRUCTION: Examine the slide of pancreas
OBSERVE- Its endocrine part in the form
of islets of Langerhan which are stained pale.
FUNCTION- Secrets digestiveexocrine
hormones & endocrine hormones
Draw the diagram ofpancreas & label it.
References:
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1. Wheaters FunctionalHistology; atext book and colour atlas, 5 th edition.
2. Text book of human histologywith colour atlas, 5 th edition, Inderbir singh.