CAT Lab 4 - Epithelium and Glands - Revised Numbering

7/31/2019 CAT Lab 4 - Epithelium and Glands - Revised Numbering

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Cells and Tissues Module Page 1

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.

Documents

CAT Lab 4 - Epithelium and Glands - Revised Numbering