EPITHELIAL EPITHELIAL TISSUETISSUE

EPITHELIAL EPITHELIAL TISSUETISSUE

DefinitionDefinitionDefinitionDefinition

Tightly-bound contiguous cells Tightly-bound contiguous cells forming sheets covering the body forming sheets covering the body surface or lining the body cavities surface or lining the body cavities and their invaginated glands.and their invaginated glands.

They are derived from the three They are derived from the three embryonic layers (ectoderm, embryonic layers (ectoderm, mesoderm and endoderm).mesoderm and endoderm).

Tightly-bound contiguous cells Tightly-bound contiguous cells forming sheets covering the body forming sheets covering the body surface or lining the body cavities surface or lining the body cavities and their invaginated glands.and their invaginated glands.

They are derived from the three They are derived from the three embryonic layers (ectoderm, embryonic layers (ectoderm, mesoderm and endoderm).mesoderm and endoderm).

CharacteristicsCharacteristicsCharacteristicsCharacteristics1.1. Cells are tightly bounded together.Cells are tightly bounded together.2.2. Little intercellular spaces and Little intercellular spaces and

extracellular matrix.extracellular matrix.3.3. Separated from the underlying Separated from the underlying

connective tissue by basal lamina.connective tissue by basal lamina.4.4. Avascular and it is nourished by Avascular and it is nourished by

diffusion from underlying tissues.diffusion from underlying tissues.5.5. Have a high rate of regeneration.Have a high rate of regeneration.

1.1. Cells are tightly bounded together.Cells are tightly bounded together.2.2. Little intercellular spaces and Little intercellular spaces and

extracellular matrix.extracellular matrix.3.3. Separated from the underlying Separated from the underlying

connective tissue by basal lamina.connective tissue by basal lamina.4.4. Avascular and it is nourished by Avascular and it is nourished by

diffusion from underlying tissues.diffusion from underlying tissues.5.5. Have a high rate of regeneration.Have a high rate of regeneration.

FunctionsFunctionsFunctionsFunctions1.1. Protection.Protection.2.2. Trans-cellular transport.Trans-cellular transport.3.3. Secretion.Secretion.4.4. Absorption.Absorption.5.5. Selective permeability.Selective permeability.6.6. Sensation.Sensation.7.7. Digestion.Digestion.8.8. Excretion.Excretion.

1.1. Protection.Protection.2.2. Trans-cellular transport.Trans-cellular transport.3.3. Secretion.Secretion.4.4. Absorption.Absorption.5.5. Selective permeability.Selective permeability.6.6. Sensation.Sensation.7.7. Digestion.Digestion.8.8. Excretion.Excretion.

NomenclatureNomenclatureNomenclatureNomenclature Epidermis for external surface.Epidermis for external surface.

Mesothelium for body cavities.Mesothelium for body cavities.

Endothelium for blood vessels.Endothelium for blood vessels.

Neuroepithelium.Neuroepithelium.

Glandular epithelium.Glandular epithelium.

Epidermis for external surface.Epidermis for external surface.

Mesothelium for body cavities.Mesothelium for body cavities.

Endothelium for blood vessels.Endothelium for blood vessels.

Neuroepithelium.Neuroepithelium.

Glandular epithelium.Glandular epithelium.

Simple SquamousSimple SquamousSimple SquamousSimple SquamousSingle layer of flat cells with central Single layer of flat cells with central

nuclei.nuclei.Function:Function:

Exchange of gases and fluids.Exchange of gases and fluids.Sites:Sites:

Lung alveoli, endothelium, Lung alveoli, endothelium, mesothelium, parietal layer of mesothelium, parietal layer of Bowman’s capsule and thin Bowman’s capsule and thin segments of loop of Henle.segments of loop of Henle.

Single layer of flat cells with central Single layer of flat cells with central nuclei.nuclei.

Function:Function:Exchange of gases and fluids.Exchange of gases and fluids.

Sites:Sites:Lung alveoli, endothelium, Lung alveoli, endothelium,

mesothelium, parietal layer of mesothelium, parietal layer of Bowman’s capsule and thin Bowman’s capsule and thin segments of loop of Henle.segments of loop of Henle.

Simple ColumnarSimple ColumnarSimple ColumnarSimple ColumnarSingle layer of tall cylindrical or Single layer of tall cylindrical or

hexagonal cells with oval basal nuclei.hexagonal cells with oval basal nuclei.Function:Function:

Secretion, absorption, transport.Secretion, absorption, transport.Sites:Sites:

Digestive tract & gall bladder Digestive tract & gall bladder (microvilli), large ducts and female (microvilli), large ducts and female genital ducts & small bronchi (cilia).genital ducts & small bronchi (cilia).

Single layer of tall cylindrical or Single layer of tall cylindrical or hexagonal cells with oval basal nuclei.hexagonal cells with oval basal nuclei.

Function:Function:Secretion, absorption, transport.Secretion, absorption, transport.

Sites:Sites:Digestive tract & gall bladder Digestive tract & gall bladder

(microvilli), large ducts and female (microvilli), large ducts and female genital ducts & small bronchi (cilia).genital ducts & small bronchi (cilia).

Pseudostratified ColumnarPseudostratified ColumnarPseudostratified ColumnarPseudostratified Columnar

Single layer of cells, all rest on basal Single layer of cells, all rest on basal lamina but not all reach to surface, with lamina but not all reach to surface, with nuclei arranged in many rows.nuclei arranged in many rows.

Function:Function:Protection, secretion, absorption.Protection, secretion, absorption.

Sites:Sites:Respiratory tract ( kinetic cilia).Respiratory tract ( kinetic cilia).Epididymis & vas deferens (stereocelia)Epididymis & vas deferens (stereocelia)

Single layer of cells, all rest on basal Single layer of cells, all rest on basal lamina but not all reach to surface, with lamina but not all reach to surface, with nuclei arranged in many rows.nuclei arranged in many rows.

Function:Function:Protection, secretion, absorption.Protection, secretion, absorption.

Sites:Sites:Respiratory tract ( kinetic cilia).Respiratory tract ( kinetic cilia).Epididymis & vas deferens (stereocelia)Epididymis & vas deferens (stereocelia)

Stratified SquamousStratified SquamousStratified SquamousStratified SquamousBasal cells are cuboidal, next layers Basal cells are cuboidal, next layers

are polygonal, the surface cells are are polygonal, the surface cells are flattened.flattened.

Function:Function:protection.protection.

Sites:Sites:Epidermis (keratinized).Epidermis (keratinized).Oral cavity, oropharynx, esophagus Oral cavity, oropharynx, esophagus

& vagina (non-keratinized).& vagina (non-keratinized).

Basal cells are cuboidal, next layers Basal cells are cuboidal, next layers are polygonal, the surface cells are are polygonal, the surface cells are flattened.flattened.

Function:Function:protection.protection.

Sites:Sites:Epidermis (keratinized).Epidermis (keratinized).Oral cavity, oropharynx, esophagus Oral cavity, oropharynx, esophagus

& vagina (non-keratinized).& vagina (non-keratinized).

Stratified CuboidalStratified CuboidalStratified CuboidalStratified Cuboidal

Two layers of cuboidal cells.Two layers of cuboidal cells.Function:Function:

transport.transport.Sites:Sites:

Duct of sweat glands.Duct of sweat glands.

Two layers of cuboidal cells.Two layers of cuboidal cells.Function:Function:

transport.transport.Sites:Sites:

Duct of sweat glands.Duct of sweat glands.

Stratified ColumnarStratified ColumnarStratified ColumnarStratified ColumnarBasal cells are cuboidal, next layers Basal cells are cuboidal, next layers

are polygonal, the surface cells are are polygonal, the surface cells are columnar.columnar.

Function:Function:Protection and transport.Protection and transport.

Sites:Sites:Conjunctiva of the eye.Conjunctiva of the eye.Large ducts.Large ducts.Parts of male urethraParts of male urethra

Basal cells are cuboidal, next layers Basal cells are cuboidal, next layers are polygonal, the surface cells are are polygonal, the surface cells are columnar.columnar.

Function:Function:Protection and transport.Protection and transport.

Sites:Sites:Conjunctiva of the eye.Conjunctiva of the eye.Large ducts.Large ducts.Parts of male urethraParts of male urethra

Transitional epitheliumTransitional epitheliumTransitional epitheliumTransitional epitheliumBasal cells are cuboidal or low columnar, Basal cells are cuboidal or low columnar,

next layers are polygonal, the surface next layers are polygonal, the surface cells are columnar, dome-shaped cells are columnar, dome-shaped binucleated (in empty bladder), but binucleated (in empty bladder), but change to flattened cell in full bladder.change to flattened cell in full bladder.

Function:Function:Protection, transport & adaptation for Protection, transport & adaptation for

stretch.stretch.Sites:Sites:

Urinary tract (calyces, renal pelvis, Urinary tract (calyces, renal pelvis, ureter, bladder and parts of urethra)ureter, bladder and parts of urethra)

Basal cells are cuboidal or low columnar, Basal cells are cuboidal or low columnar, next layers are polygonal, the surface next layers are polygonal, the surface cells are columnar, dome-shaped cells are columnar, dome-shaped binucleated (in empty bladder), but binucleated (in empty bladder), but change to flattened cell in full bladder.change to flattened cell in full bladder.

Function:Function:Protection, transport & adaptation for Protection, transport & adaptation for

stretch.stretch.Sites:Sites:

Urinary tract (calyces, renal pelvis, Urinary tract (calyces, renal pelvis, ureter, bladder and parts of urethra)ureter, bladder and parts of urethra)

Polarity and cell curface Polarity and cell curface specializationsspecializations

Polarity and cell curface Polarity and cell curface specializationsspecializations

Epithelial cells have many Epithelial cells have many surface modifications and surface modifications and specializations related to their specializations related to their distinct functionalities.distinct functionalities.

These specializations occur at all These specializations occur at all the cell surfaces (apical, lateral the cell surfaces (apical, lateral and basal surfaces).and basal surfaces).

Epithelial cells have many Epithelial cells have many surface modifications and surface modifications and specializations related to their specializations related to their distinct functionalities.distinct functionalities.

These specializations occur at all These specializations occur at all the cell surfaces (apical, lateral the cell surfaces (apical, lateral and basal surfaces).and basal surfaces).

Apical specializationsApical specializationsApical specializationsApical specializations

1.1. Microvilli.Microvilli.

2.2. Cilia.Cilia.

3.3. Flagella.Flagella.

4.4. Cell coat (glycocalyx).Cell coat (glycocalyx).

1.1. Microvilli.Microvilli.

2.2. Cilia.Cilia.

3.3. Flagella.Flagella.

4.4. Cell coat (glycocalyx).Cell coat (glycocalyx).

MicrovilliMicrovilliMicrovilliMicrovilli Are small finger-like processes projecting from Are small finger-like processes projecting from

the free surface of the cell into the lumen.the free surface of the cell into the lumen. They increase the surface area of the cell to They increase the surface area of the cell to

increase its absorption.increase its absorption. Contain 25-30 actin filaments attached to the Contain 25-30 actin filaments attached to the

apex of the villus in the dense lip.apex of the villus in the dense lip. At the base of the villus, the actin filament are At the base of the villus, the actin filament are

attached to the terminal web.attached to the terminal web. Microvilli form the brush border of the Microvilli form the brush border of the

convoluted tubule of kidney and striated convoluted tubule of kidney and striated border of the small intestine epithelial cells. border of the small intestine epithelial cells.

Are small finger-like processes projecting from Are small finger-like processes projecting from the free surface of the cell into the lumen.the free surface of the cell into the lumen.

They increase the surface area of the cell to They increase the surface area of the cell to increase its absorption.increase its absorption.

Contain 25-30 actin filaments attached to the Contain 25-30 actin filaments attached to the apex of the villus in the dense lip.apex of the villus in the dense lip.

At the base of the villus, the actin filament are At the base of the villus, the actin filament are attached to the terminal web.attached to the terminal web.

Microvilli form the brush border of the Microvilli form the brush border of the convoluted tubule of kidney and striated convoluted tubule of kidney and striated border of the small intestine epithelial cells. border of the small intestine epithelial cells.

CiliaCiliaCiliaCilia Are long motile hair-like processes projecting Are long motile hair-like processes projecting

from the free surface of the cell into the from the free surface of the cell into the lumen.lumen.

Cilia propel the mucus and other structure Cilia propel the mucus and other structure over the surface of the epithelium by rapid over the surface of the epithelium by rapid rhythmic oscillations.rhythmic oscillations.

Its core is formed of microtubule arranged in Its core is formed of microtubule arranged in axoneme (2 singlets surrounded by 9 axoneme (2 singlets surrounded by 9 doublets).doublets).

The cilium is attached to basal body (9 triplets The cilium is attached to basal body (9 triplets with no singlet).with no singlet).

Are long motile hair-like processes projecting Are long motile hair-like processes projecting from the free surface of the cell into the from the free surface of the cell into the lumen.lumen.

Cilia propel the mucus and other structure Cilia propel the mucus and other structure over the surface of the epithelium by rapid over the surface of the epithelium by rapid rhythmic oscillations.rhythmic oscillations.

Its core is formed of microtubule arranged in Its core is formed of microtubule arranged in axoneme (2 singlets surrounded by 9 axoneme (2 singlets surrounded by 9 doublets).doublets).

The cilium is attached to basal body (9 triplets The cilium is attached to basal body (9 triplets with no singlet).with no singlet).

FlagellaFlagellaFlagellaFlagella

Are similar to cilia, but single Are similar to cilia, but single

and very long.and very long.

Present only in the Present only in the

spermatozoa.spermatozoa.

Are similar to cilia, but single Are similar to cilia, but single

and very long.and very long.

Present only in the Present only in the

spermatozoa.spermatozoa.

GlycocalyxGlycocalyxGlycocalyxGlycocalyx Glycoprotein attached to the external Glycoprotein attached to the external

surface of the cell membrane.surface of the cell membrane. Formed of carbohydrate chain Formed of carbohydrate chain

attached to the transmembrane protein attached to the transmembrane protein of the plasmalemma.of the plasmalemma.

Contains some hydrolytic enzymes Contains some hydrolytic enzymes and alkaline phosphatase.and alkaline phosphatase.

They function in protection and cell They function in protection and cell recognition.recognition.

Glycoprotein attached to the external Glycoprotein attached to the external surface of the cell membrane.surface of the cell membrane.

Formed of carbohydrate chain Formed of carbohydrate chain attached to the transmembrane protein attached to the transmembrane protein of the plasmalemma.of the plasmalemma.

Contains some hydrolytic enzymes Contains some hydrolytic enzymes and alkaline phosphatase.and alkaline phosphatase.

They function in protection and cell They function in protection and cell recognition.recognition.

Lateral specializationsLateral specializationsLateral specializationsLateral specializations

1.1. Occluding (tight) junction.Occluding (tight) junction.

2.2. Adhering junction.Adhering junction.

3.3. Desmosome.Desmosome.

4.4. Gap junction.Gap junction.

1.1. Occluding (tight) junction.Occluding (tight) junction.

2.2. Adhering junction.Adhering junction.

3.3. Desmosome.Desmosome.

4.4. Gap junction.Gap junction.

Tight JunctionsTight JunctionsTight JunctionsTight Junctions Called also zonulae occludentes.Called also zonulae occludentes. Located between the adjacent plasma Located between the adjacent plasma

membranes.membranes. Are the most apically located junction.Are the most apically located junction. Form belt-like junction at all circumference.Form belt-like junction at all circumference. The outer leaflets of the two cell membrane The outer leaflets of the two cell membrane

fuse together.fuse together. Its function to prevent membrane proteins Its function to prevent membrane proteins

and water-soluble molecules from passing and water-soluble molecules from passing between the cells.between the cells.

Called also zonulae occludentes.Called also zonulae occludentes. Located between the adjacent plasma Located between the adjacent plasma

membranes.membranes. Are the most apically located junction.Are the most apically located junction. Form belt-like junction at all circumference.Form belt-like junction at all circumference. The outer leaflets of the two cell membrane The outer leaflets of the two cell membrane

fuse together.fuse together. Its function to prevent membrane proteins Its function to prevent membrane proteins

and water-soluble molecules from passing and water-soluble molecules from passing between the cells.between the cells.

Adhering JunctionsAdhering JunctionsAdhering JunctionsAdhering Junctions Called also zonulae adherentes.Called also zonulae adherentes. It is a junctional complex that lies just basal It is a junctional complex that lies just basal

to the tight junction.to the tight junction. The intercellular space between the outer The intercellular space between the outer

leaflets is occupied by transmembrane leaflets is occupied by transmembrane linker protein, which in turn is attached to linker protein, which in turn is attached to actin filaments of both adjacent cells.actin filaments of both adjacent cells.

Function is not only joins the two cell Function is not only joins the two cell membranes to each other, but also links membranes to each other, but also links the cytoskeleton of both cells.the cytoskeleton of both cells.

Called also zonulae adherentes.Called also zonulae adherentes. It is a junctional complex that lies just basal It is a junctional complex that lies just basal

to the tight junction.to the tight junction. The intercellular space between the outer The intercellular space between the outer

leaflets is occupied by transmembrane leaflets is occupied by transmembrane linker protein, which in turn is attached to linker protein, which in turn is attached to actin filaments of both adjacent cells.actin filaments of both adjacent cells.

Function is not only joins the two cell Function is not only joins the two cell membranes to each other, but also links membranes to each other, but also links the cytoskeleton of both cells.the cytoskeleton of both cells.

DesmosomesDesmosomesDesmosomesDesmosomes Called also maculae adherentes.Called also maculae adherentes. Are weld-like junctions that help to resist Are weld-like junctions that help to resist

the shearing forces.the shearing forces. Disk-shaped attachment plaques lying Disk-shaped attachment plaques lying

opposite each other on the cytoplasmic opposite each other on the cytoplasmic aspects of plasma membrane of adjacent aspects of plasma membrane of adjacent epithelial cells.epithelial cells.

Intermediate filaments are inserted to these Intermediate filaments are inserted to these plaques, these filaments are responsible for plaques, these filaments are responsible for dispersing the shearing forces on the cell.dispersing the shearing forces on the cell.

Called also maculae adherentes.Called also maculae adherentes. Are weld-like junctions that help to resist Are weld-like junctions that help to resist

the shearing forces.the shearing forces. Disk-shaped attachment plaques lying Disk-shaped attachment plaques lying

opposite each other on the cytoplasmic opposite each other on the cytoplasmic aspects of plasma membrane of adjacent aspects of plasma membrane of adjacent epithelial cells.epithelial cells.

Intermediate filaments are inserted to these Intermediate filaments are inserted to these plaques, these filaments are responsible for plaques, these filaments are responsible for dispersing the shearing forces on the cell.dispersing the shearing forces on the cell.

Gap JunctionsGap JunctionsGap JunctionsGap Junctions Called also nexus or communicating Called also nexus or communicating

junctions.junctions. Present in epithelial cells, cardiac and Present in epithelial cells, cardiac and

smooth muscles and neurons.smooth muscles and neurons. They are tiny pores communcating They are tiny pores communcating

between two adjacent cells and permit the between two adjacent cells and permit the passage of ions, amino acids, AMP and passage of ions, amino acids, AMP and certain hormones between the cells.certain hormones between the cells.

They are under regulation, so they may be They are under regulation, so they may be opened or closed.opened or closed.

Called also nexus or communicating Called also nexus or communicating junctions.junctions.

Present in epithelial cells, cardiac and Present in epithelial cells, cardiac and smooth muscles and neurons.smooth muscles and neurons.

They are tiny pores communcating They are tiny pores communcating between two adjacent cells and permit the between two adjacent cells and permit the passage of ions, amino acids, AMP and passage of ions, amino acids, AMP and certain hormones between the cells.certain hormones between the cells.

They are under regulation, so they may be They are under regulation, so they may be opened or closed.opened or closed.

Basal specializationsBasal specializationsBasal specializationsBasal specializations

1.1. Basement membrane.Basement membrane.

2.2. Plasma membrane Plasma membrane

enfolding.enfolding.

3.3. Hemi-desmosome.Hemi-desmosome.

1.1. Basement membrane.Basement membrane.

2.2. Plasma membrane Plasma membrane

enfolding.enfolding.

3.3. Hemi-desmosome.Hemi-desmosome.

Plasma Membrane EnfoldingPlasma Membrane EnfoldingPlasma Membrane EnfoldingPlasma Membrane Enfolding

Multiple basal enfolding of cell membrane Multiple basal enfolding of cell membrane to increase the surface area for transport.to increase the surface area for transport.

It make many partitions in the basal part of It make many partitions in the basal part of the cells which are occupied by finger-like the cells which are occupied by finger-like mitochondria giving the cell striated-mitochondria giving the cell striated-appearance.appearance.

Present in the ducts of pancreas and Present in the ducts of pancreas and salivary glands and are called striated salivary glands and are called striated ducts.ducts.

Multiple basal enfolding of cell membrane Multiple basal enfolding of cell membrane to increase the surface area for transport.to increase the surface area for transport.

It make many partitions in the basal part of It make many partitions in the basal part of the cells which are occupied by finger-like the cells which are occupied by finger-like mitochondria giving the cell striated-mitochondria giving the cell striated-appearance.appearance.

Present in the ducts of pancreas and Present in the ducts of pancreas and salivary glands and are called striated salivary glands and are called striated ducts.ducts.

Hemi-desmosomesHemi-desmosomesHemi-desmosomesHemi-desmosomes Attach the basal cell membrane to Attach the basal cell membrane to

the underlying basal lamina.the underlying basal lamina. They resemble half desmosomes.They resemble half desmosomes. Attachment plaques are present on Attachment plaques are present on

the cytoplasmic aspect of cell the cytoplasmic aspect of cell membrane, tonofilaments are membrane, tonofilaments are attached to these plaques.attached to these plaques.

Attach the basal cell membrane to Attach the basal cell membrane to the underlying basal lamina.the underlying basal lamina.

They resemble half desmosomes.They resemble half desmosomes. Attachment plaques are present on Attachment plaques are present on

the cytoplasmic aspect of cell the cytoplasmic aspect of cell membrane, tonofilaments are membrane, tonofilaments are attached to these plaques.attached to these plaques.

Glandular EpitheliumGlandular EpitheliumGlandular EpitheliumGlandular Epithelium Glands originate from the epithelial Glands originate from the epithelial

surface, penetrate the underlying surface, penetrate the underlying connective tissue and manufacture a connective tissue and manufacture a basal lamina around themselves.basal lamina around themselves.

The parenchyma represents the The parenchyma represents the secretory units and the duct system, secretory units and the duct system, while stroma is the connective tissue while stroma is the connective tissue between the parenchyma.between the parenchyma.

Glands originate from the epithelial Glands originate from the epithelial surface, penetrate the underlying surface, penetrate the underlying connective tissue and manufacture a connective tissue and manufacture a basal lamina around themselves.basal lamina around themselves.

The parenchyma represents the The parenchyma represents the secretory units and the duct system, secretory units and the duct system, while stroma is the connective tissue while stroma is the connective tissue between the parenchyma.between the parenchyma.

ClassificationClassificationClassificationClassification There are many ways for There are many ways for

classification of glands according classification of glands according to mode of secretion, type of to mode of secretion, type of secretion, way of secretion, secretion, way of secretion, number of secretory cells, duct number of secretory cells, duct system and shape of the system and shape of the secretory units.secretory units.

There are many ways for There are many ways for classification of glands according classification of glands according to mode of secretion, type of to mode of secretion, type of secretion, way of secretion, secretion, way of secretion, number of secretory cells, duct number of secretory cells, duct system and shape of the system and shape of the secretory units.secretory units.

According to presence of ductsAccording to presence of ductsAccording to presence of ductsAccording to presence of ducts

1.1. Exocrine glandExocrine gland: means it pours its : means it pours its secretion through duct system to a secretion through duct system to a particular place, e.g. salivary glands.particular place, e.g. salivary glands.

2.2. Endocrine glandEndocrine gland: has no ducts and it : has no ducts and it delivers its secretion directly to the delivers its secretion directly to the blood stream, e.g. thyroid gland.blood stream, e.g. thyroid gland.

3.3. Mixocrine glandMixocrine gland: has both types, e.g. : has both types, e.g. pancreas.pancreas.

1.1. Exocrine glandExocrine gland: means it pours its : means it pours its secretion through duct system to a secretion through duct system to a particular place, e.g. salivary glands.particular place, e.g. salivary glands.

2.2. Endocrine glandEndocrine gland: has no ducts and it : has no ducts and it delivers its secretion directly to the delivers its secretion directly to the blood stream, e.g. thyroid gland.blood stream, e.g. thyroid gland.

3.3. Mixocrine glandMixocrine gland: has both types, e.g. : has both types, e.g. pancreas.pancreas.

According to type of secretionAccording to type of secretionAccording to type of secretionAccording to type of secretion

1.1. MucousMucous: sublingual (salivary), Brunner’s : sublingual (salivary), Brunner’s glands (in duodenum) and goblets cells.glands (in duodenum) and goblets cells.

2.2. SerousSerous: parotid salivary gland.: parotid salivary gland.3.3. SeromucousSeromucous: Sunmandibular.: Sunmandibular.4.4. WaxyWaxy: ceruminous gland (external ear).: ceruminous gland (external ear).5.5. FattyFatty: sebaceous glands.: sebaceous glands.6.6. WateryWatery: sweat glands.: sweat glands.7.7. MilkMilk: mammary glands.: mammary glands.8.8. CellularCellular: testis: testis

1.1. MucousMucous: sublingual (salivary), Brunner’s : sublingual (salivary), Brunner’s glands (in duodenum) and goblets cells.glands (in duodenum) and goblets cells.

2.2. SerousSerous: parotid salivary gland.: parotid salivary gland.3.3. SeromucousSeromucous: Sunmandibular.: Sunmandibular.4.4. WaxyWaxy: ceruminous gland (external ear).: ceruminous gland (external ear).5.5. FattyFatty: sebaceous glands.: sebaceous glands.6.6. WateryWatery: sweat glands.: sweat glands.7.7. MilkMilk: mammary glands.: mammary glands.8.8. CellularCellular: testis: testis

According to mode of secretionAccording to mode of secretionAccording to mode of secretionAccording to mode of secretion

1.1. Holocrine glandHolocrine gland: The whole cell is : The whole cell is destroyed and detached, e.g. destroyed and detached, e.g. sebaceous gland.sebaceous gland.

2.2. Merocrine glandMerocrine gland: The cell is intact and : The cell is intact and it secretes through exocytosis of it secretes through exocytosis of secretory vesicles, e.g. salivary secretory vesicles, e.g. salivary glands.glands.

3.3. Apocrine glandApocrine gland: the apical part of the : the apical part of the cell is detached, e.g. mammary gland.cell is detached, e.g. mammary gland.

1.1. Holocrine glandHolocrine gland: The whole cell is : The whole cell is destroyed and detached, e.g. destroyed and detached, e.g. sebaceous gland.sebaceous gland.

2.2. Merocrine glandMerocrine gland: The cell is intact and : The cell is intact and it secretes through exocytosis of it secretes through exocytosis of secretory vesicles, e.g. salivary secretory vesicles, e.g. salivary glands.glands.

3.3. Apocrine glandApocrine gland: the apical part of the : the apical part of the cell is detached, e.g. mammary gland.cell is detached, e.g. mammary gland.

According to number of cellsAccording to number of cellsAccording to number of cellsAccording to number of cells

1.1. Unicellular glandUnicellular gland: one cell only, : one cell only, e.g. goblet cells in the epithelium of e.g. goblet cells in the epithelium of mucosa of respiratory tracts and mucosa of respiratory tracts and intestine.intestine.

2.2. Multicellular glandMulticellular gland: Many cells and : Many cells and they pour their secretion into the they pour their secretion into the duct system, e.g. salivary glands.duct system, e.g. salivary glands.

1.1. Unicellular glandUnicellular gland: one cell only, : one cell only, e.g. goblet cells in the epithelium of e.g. goblet cells in the epithelium of mucosa of respiratory tracts and mucosa of respiratory tracts and intestine.intestine.

2.2. Multicellular glandMulticellular gland: Many cells and : Many cells and they pour their secretion into the they pour their secretion into the duct system, e.g. salivary glands.duct system, e.g. salivary glands.

Simple glandsSimple glandsSimple glandsSimple glands

1.1. Simple tubularSimple tubular: as in : as in intestine.intestine.

2.2. Simple coiled tubularSimple coiled tubular: as : as sweat glands.sweat glands.

3.3. Simple acinarSimple acinar..4.4. Simple tubulo-acinarSimple tubulo-acinar..

1.1. Simple tubularSimple tubular: as in : as in intestine.intestine.

2.2. Simple coiled tubularSimple coiled tubular: as : as sweat glands.sweat glands.

3.3. Simple acinarSimple acinar..4.4. Simple tubulo-acinarSimple tubulo-acinar..

Branched glandsBranched glandsBranched glandsBranched glands

1.1. Branched tubularBranched tubular: as in : as in stomach.stomach.

2.2. Branched acinarBranched acinar: as : as sebaceous glands.sebaceous glands.

3.3. Branched tubulo-acinarBranched tubulo-acinar: as : as glands of oral cavityglands of oral cavity..

1.1. Branched tubularBranched tubular: as in : as in stomach.stomach.

2.2. Branched acinarBranched acinar: as : as sebaceous glands.sebaceous glands.

3.3. Branched tubulo-acinarBranched tubulo-acinar: as : as glands of oral cavityglands of oral cavity..

Compound glandsCompound glandsCompound glandsCompound glands

1.1. Compound tubularCompound tubular: as in : as in kidney and liver.kidney and liver.

2.2. Compound acinarCompound acinar: as : as sebaceous glands.sebaceous glands.

3.3. Compound tubulo-acinarCompound tubulo-acinar: as : as pancreas and salivary glandspancreas and salivary glands..

1.1. Compound tubularCompound tubular: as in : as in kidney and liver.kidney and liver.

2.2. Compound acinarCompound acinar: as : as sebaceous glands.sebaceous glands.

3.3. Compound tubulo-acinarCompound tubulo-acinar: as : as pancreas and salivary glandspancreas and salivary glands..