Tongue histology viva questions

Tongue:

1. What are the layers of tongue?
• Mucosa
• Partially keratinized stratified squamous epithelium
• Lamina propria
• Thick muscular layer
2. Why is epithelium rough on dorsal surface?
• The epithelium is rough on dorsal surface due to the projections called papillae
3. Name 4 types of papillae/ what are the 4 types of papillae?
• Filiform
• Fungiform
• Circumvallate
• Foliate
4. Which papillae is not seen in humans / which papillae is absent in humans?
• Foliate
5. Which papillae are more numerous?
• Filiform is more numerous covering entire anterior 2/3rd of dorsal surface of tongue
6. Which papillae is keratinized and which are non-keratinized?
• Filiform is keratinized
• Fungiform and circumvallate are non keratinized
7. What is the distribution of fungiform papillae?
• It is distributed at the tip and sides of tongue
8. What is the distribution of circumvallate papillae?
• Around 12 to 15 circumvallate papillae are present at the junction of anterior 2/3rd and posterior 1/3rd of the tongue
9. Describe filiform papillae
• Filiform papillae are bent sharp conical projections of epithelium directed posteriorly. It is partially covered by keratin at the tip
10. Describe fungiform papillae
• They are mushroom shaped larger, taller and broader papillae
• It has core of lamina propria surrounded by non-keratinized stratified squamous epithelium
• Few taste buds may be present towards surface of epithelium
11. Describe circumvallate papillae
• It is surrounded by deep trench or furrow. It is lined by non-keratinized stratified squamous epithelium with a core of lamina propria
• Lamina propria has numerous secondary papillae projecting into epithelium. It has connective tissue, blood vessels, nerves,  lymphatics and  von Ebner’s glands which open into trench
• Taste buds are present on lateral walls
12. Where are the taste buds present?
• They extend along the whole thickness of epithelium in lateral wall of circumvallate papillae and on surface epithelium of fungiform papillae 
13. Describe taste buds
• Sustentacular cells or supporting cells- elongated with dark cytoplasm and slender dark nucleus
• Gustatory cells or taste cells or sensory cells or neuroepithelial cells-  lighter cytoplasm and oval light nucleus
• Basal cells near basement membrane of taste bud
• It has a small opening in the center which opens towards the epithelial surface
14. What are intragemmal and intergemmal fibers?
• Intragemmal fibers-  sensory fibers ending within the taste buds
• Intergemmal fibers-  fibers ending freely in epithelium in between taste cells
15. Name the components of lamina propria
• Loose connective tissue
• Blood vessels
• Nerves
• Lymphatics
16. What is the arrangement of muscular layer
• Muscular layer is very thick and fibers are arranged in various directions

digestive system general structure viva questions

Digestive system general structure:

1. What is the function of digestive system?
• The function of digestive system is to obtain molecules from the ingested food which is necessary for the maintenance, growth and energy needs of the body 
2. What happens during digestion? or what is digestion?
• The digestion is the process where proteins, complex carbohydrates, nucleic acids and fats are broken down into small molecules which can be easily absorbed by the small intestine
3. What are the four main layers of digestive tract?
• From within (lumen) outwards
• Mucosa (mucous membrane)
• Submucosa
• Muscularis externa
• Serosa or adventitia
4. What are the layers of mucosa?
• From lumen outwards
• Epithelial lining
• Lamina propria
• Muscularis mucosae
5. What are the different types of epithelial lining observed in the digestive tract?
• Stratified squamous non-keratinized epithelium (mouth, esophagus)
• Simple columnar epithelium (stomach, intestine)
• Tall columnar ciliated epithelium (gall bladder)
6. What are the components of lamina propria?
• Loose connective tissue
• Blood vessels
• Lymphatics
• Lymphocytes
• Smooth muscle cells
• Glands
7. What is muscularis mucosae?
• Muscularis mucosae is a thin layer of smooth muscle arranged as inner circular and outer longitudinal layers around the lamina propria
8. What are the components of submucosa?
• Dense connective tissue
• larger blood vessels
• Glands and lymphoid tissue in few parts of the tract
• Submucosal (Meissner's) plexus of autonomic nerves
9. What are the components of muscularis externa?
• Inner circular smooth muscle layer
• Outer longitudinal smooth muscle layer
• Between two layers is thin connective tissue layer with blood vessels, lymph vessels, myenteric (Auerbach's) plexus of autonomic nerves
10. What is serosa or adventitia? Difference between serosa and adventitia
• Serosa- thin layer of loose connective tissue with numerous blood vessels, lymphatics, adipose tissue covered by simple squamous epithelium (mesothelium)
• Adventitia- loose connective tissue with numerous blood vessels, lymphatics, adipose tissue which merges with surrounding tissues. Mesothelium is absent
11. What is mesothelium?
• It is a simple squamous epithelium covering a thin layer of loose connective tissue in the abdomen surrounding the viscera
12. What is the function of Meissner's plexus?
• Meissner’s plexus regulates the configuration of the luminal surface, controls glandular
  secretions, alters electrolyte and water transport and regulates local blood flow
13. What is the function of Myenteric plexus?
• Myenteric plexus supplies the GIT and controls the gastric motility

respiratory system- discussion, viva

Respiratory system:

1. Name the parts of respiratory system.
• Upper respiratory tract
• Nasal cavity
• Pharynx
• Larynx
• Lower respiratory tract
• Trachea
• Extrapulmonary bronchi or primary bronchi
• Intrapulmonary bronchi 
• Secondary bronchi or lobar bronchi
• Tertiary bronchi or segmental bronchi
• Bronchioles
• Terminal bronchioles
• Respiratory bronchioles
• Alveolar duct
• Alveolar sac
• Alveoli
2. Classify respiratory system on functional basis.
• Conducting portion- From trachea to terminal bronchiole
• Transition zone- respiratory bronchiole 
• Respiratory portion-  from alveolar duct to alveoli 
3. Name the functions of conducting, transition and respiratory portions.
• Conducting portion- conducts air to and from lungs, cleans and humidifies air
• Transition zone- conducts air and also exchange of gases
• Respiratory portion-  exchange of gases 
4. Name the cells in the respiratory passage.
• Tall columnar ciliated cells
• Basal cells
• Goblet cells
• Clara cells
• Brush cells (non-ciliated columnar cells)
• Small granule cells (Kulchitsky cells)
• Type 1 alveolar cells (type 1 pneumocytes)
• Type 2 alveolar cells (type 2 pneumocytes)
• Dust cells (alveolar macrophage cells)

Trachea:

1. Name the layers of trachea?
• From luminal surface to outwards
• Mucosa- 1. epithelial lining, 2. lamina propria
• Submucosa
• Fibromusculocartilagenous layer
• Adventitia
2. What is the epithelium lining the trachea?
• Pseudostratified ciliated columnar epithelium which has tall columnar ciliated cells and basal cells
3. Name the contents of lamina propria.
• Loose connective tissue
• Lymphocytes
• Blood vessels
• Seromucous glands, mainly mucous
4. Name the components of submucosa.
• Dense connective tissue
• Seromucous glands
5. Why the third layer is called fibromusculocartilagenous layer?
• The layer is made of 
• C-shaped hyaline cartilage which is deficient posteriorly.
• Smooth muscle bundle called trachealis muscle binds to two ends of hyaline cartilage
• Fibroelastic tissue mixed with smooth muscle
• Since this layer has all the three parts- cartilage, smooth muscle and fibroelastic tissue, it is called as fibromusculocartilagenous layer
6. Give the structure of hyaline cartilage.
• See the post on cartilage
7. What is adventitia made of?
• Connective tissue
• Blood vessels
• Nerves

Lung:

1. What are the components of lung?
• Intrapulmonary bronchi- secondary and tertiary bronchi
• Bronchioles- terminal and respiratory bronchioles
• Alveolar duct
• Alveolar sac
• Alveoli
2. What are the differences between trachea, extra pulmonary bronchus and intra pulmonary bronchus
• Refer the table below
3. What are the differences between bronchus and bronchiole?
• Refer the table below
4. Name the cells present in the walls of the alveoli.
• Type 1 alveolar cells (type 1 pneumocytes)
• Type 2 alveolar cells (type 2 pneumocytes)
• Dust cells (alveolar macrophage cells)
5. What are the functions of the cells in alveoli?
• Type 1 alveolar cells - squamous cells for exchange of gases
• Type 2 alveolar cells - cuboidal cells for secretion of surfactant
• Dust cells - macrophages for phagocytosis
6. What is blood-air barrier?
• Blood-air barrier are the layers present between blood in the capillary network and the air in the alveoli for the exchange of oxygen and carbon-dioxide.
7. Name the layers of blood-air barrier.
• Endothelial cells in the capillary
• Basal lamina of capillary
• Basal lamina of type 1 alveolar cells
• Type 1 alveolar cells

Differences between trachea and different parts of bronchial tree

Parts	Epithelium	Features of wall
Trachea	Pseudostratified ciliated columnar epithelium, goblet cells, basal cells	Lamina propria, submucosa with seromucous glands, fibromusculocartilagenous layer, adventitia
Bronchi	Pseudostratified ciliated columnar epithelium with goblet cells	Narrow thin lamina propria, layer of smooth muscle cells, submucosa with bronchial glands, irregular hyaline cartilage plates, adventitia
Bronchiole	Pseudostratified ciliated columnar to simple cuboidal epithelium from proximal to distal with occasional goblet cells, brush cells (nonciliated columnar), Kulchitsky cells (small granule cells), Clara cells	Mucosal folds, smooth muscle layer, adventitia. No cartilage and glands
Terminal bronchiole	Simple cuboidal epithelium, clara cells	Thin, incomplete layer of smooth muscle. No cartilage and glands
Respiratory bronchiole	Simple cuboidal epithelium, clara cells with scattered alveoli	Few smooth muscle fibers mostly around alveolar openings
Alveolar ducts, sacs	Simple cuboidal between many alveoli	Bands of smooth muscle around alveolar openings
Alveoli	Type 1 and type 2 alveolar cells (pneumocytes)	Only network of elastic and reticular fibers

placenta, umbilical cord- discussion, viva

Placenta:

1. Give histological structures of the placenta
• Maternal surface irregular because of cotyledons separated by placental septa. It is formed by basal plate which includes decidua basalis
• Fetal surface is smooth, covered by amnion and gives attachment to umbilical cord. It is formed by amnion, chorionic plate, chorionic villi from outside inwards
2. What is decidua basalis?
• Decidua basalis is the part of endometrium present between the implanted embryo and myometrium
3. What are chorionic villi? What are the types? 
• Chorionic villi are the finger like projections from the chorionic plate formed by cytotrophoblast and syncytiotrophoblast. 
• 3 types of chorionic villi- primary, secondary, tertiary villi
4. Give the structure of the three villi
• Primary villi- simple cord with a solid core of cytotrophoblast surrounded by syncytiotrophoblast
• Secondary villi- projection with central core of mesoderm surrounded successively by cytotrophoblast and syncytiotrophoblast
• Tertiary villi- projection with fetal blood vessels in the core of mesoderm surrounded successively by cytotrophoblast and syncytiotrophoblast. along with fetal capillaries there are fibroblasts and phagocytic cells called Hofbauer cells
5. What are anchoring villi and floating or free villi
• Anchoring villi- villi attached to chorionic plate
• Floating or free villi- the branches from anchoring villi which float in intervillous spaces
6. Name the site of exchange occurring in placenta
• Exchange occurs between the embryonic blood in chorionic villi outside the embryo and maternal blood in lacunae called intervillous spaces of decidua basalis
7. Name the layers of placental barrier
• Upto 20 weeks
• Syncytiotrophoblast
• Cytotrophoblast
• Connective tissue of villi
• Endothelium of fetal capillaries
• After 20 weeks
• Syncytiotrophoblast
• Connective tissue of villi
• Endothelium of fetal capillaries
8. What are the functions of placenta?
• Exchange of nutrients, oxygen, carbon-dioxide, wastes between mother and fetus
• Passive immunity to fetus by transfer of maternal IgG antibodies
• Secretes human chorionic gonadotrophin (hCG), estrogen, progesterone and placental lactogen

Umbilical Cord:

1. Give the structure of umbilical cord
• It is surrounded by amnion
• It consists of two umbilical arteries and one umbilical vein
• The vessels are surrounded by primary mesoderm called Wharton's jelly which protects the vessels
2. What is Wharton's jelly?
• Wharton’s jelly is a mass of loose connective tissue with fibroblasts separated by fine collagen fibers and ground substance containing hydrated glycosaminoglycans rich in hyaluronic acid. It gives cushioning effect to vessels.
3. What are the functions of umbilical arteries and vein?
• Umbilical arteries- carry deoxygenated blood from fetus to placenta
• Umbilical vein- carry oxygenated blood from placenta to fetus

epithelial / salivary glands, serous gland, mucous gland, mixed gland- discussion, viva

Epithelial / Salivary glands

1. How many salivary glands are present and where are they located?
• Serous or parotid salivary gland- largest glands located anterior and inferior to external ear
• Mucous or sublingual salivary gland- smallest glands located inferior to tongue
• Mixed or submandibular gland- small glands located inferior to mandible in the floor of mouth
2. What type of glands are salivary glands functionally?
• They are exocrine glands
3. What type of glands are salivary glands structurally?
• They are compound tubuloacinar glands
4. Where and how do they pour their secretion?
• Secretions are poured into the mouth through their large excretory ducts
5. What are the components of salivary glands?
• Cellular secretory units- acini
• Excretory ducts
6. What are acini?
• Acini are small, sac like dilations at the terminal end of intercalated ducts.
7. What are intercalated ducts?
• Intercalated ducts are the first segments of the excretory duct system attached to acini
8. What are different types of acini?
• Serous acini- made up of serous cells which are pyramidal in shape. Spherical or round nuclei are present at basal half and secretory granules in the apical region of the cells
• Mucous acini- made up of mucous cells which are columnar or pyramidal in shape. Flat nucleus present near the basement membrane and cytoplasm completely filled with mucus
• Serous demilune- Serous cells form a crescent or moon shaped cap over the mucous cells which is called serous demilune. They discharge their secretion into lumen through canaliculi present between the mucous cells
9. What are myoepithelial cells?
• Myoepithelial cells are flattened cells that surround both serous and mucous acini.
• They are highly branched and contractile in nature
• They are also called basket cells
• They are located between the basement membrane and the secretory cells
10. Details about excretory ducts
• Intercalated ducts- they are lined by low cuboidal epithelium. Initially all acini empty their secretions into intercalated ducts and part related to acini is surrounded by myoepithelial cells
• Striated ducts- intercalated join to form striated and are lined by columnar epithelium with basal infoldings of the cell membrane with numerous mitochondria which gives striated appearance
• Intralobular ducts- striated join to form intralobular ducts and are lined by columnar epithelium
• Interlobular ducts- intralobular join to form interlobular ducts and are lined by columnar epithelium
• Interlobar ducts- interlobular join to form interlobar ducts and are lined by stratified cuboidal or columnar epithelium
11. What is the arrangement of connective tissue in the glands?
• The whole gland is surrounded by connective tissue capsule.
• The gland is divided into lobes and lobules by the connective tissue fibers.
12. What are the differences between the mucous, serous and mixed salivary glands?

Types	Serous	Mucous	Mixed
Connective tissue	Well developed connective tissue capsule. Interlobular connective tissue with vessels and adipose tissue.	Well developed connective tissue capsule. Well developed connective tissue septa.	Well developed connective tissue capsule and stroma.
Acini (alveoli)	Serous.	Mucous.	Seromucous.
Cells	Pyramidal in shape with round nuclei at the base. Darkly stained apical cytoplasm because of the zymogen granules.	Globular in shape. Flat and condensed nuclei, at the basement membrane. Cells appear empty in H and E staining, because during the   processing mucinogen granules are washed off.	Both serous and mucous alveoli present. Demilunes or crescents of Gianuzzi, are the appearance of the sectioned serous alveoli seen as half moon or crescent shape over the mucous alveoli.
Duct system	Numerous inter lobular, intra lobular and  intercalated ducts. Lined by stratified to simple columnar to low cuboidal   epithelium.	Intercalated ducts are very rare or absent, more nonstriated intralobular ducts. Lined by stratified to simple columnar to low cuboidal   epithelium.	Few intercalated, more striated ducts. Lined by stratified to simple columnar to low cuboidal   epithelium. Serous demilunes discharge the secretion through the intercellular canaliculi located between the mucous cells.
Secretion	Watery secretion rich in enzymes and antibodies.	Viscid secretion.	Both watery as well as the viscid secretions.
E.g. Salivary gland	Parotid.	Sublingual.	Submandibular.

Thick skin, thin skin- discussion, viva

Skin:

1. What are the two regions/layers of skin?
• Superficial nonvascular epidermis
• Deep vascular dermis
2. What are the derivatives/ appendages of the skin?
• Nail
• Hair
• Sweat gland
• Sebaceous gland
• Arrector pili muscle
3. What are the two types of skin?
• Thick skin
• Thin skin
4. Where do you find Thick skin?
• Palm, sole
5. Where do you find thin skin?
• Whole body except palms and soles is covered by thin skin
6. What are the functions of the skin?
• Protection from mechanical abrasion, forms physical barrier to pathogens or foreign microorganisms
• Prevents the loss of body fluids
• Temperature regulation
• Acts as sensory organ responding to external stimuli like temperature, touch, pain and pressure
• Acts as excretory organ by producing sweat through which water, sodium salts, urea and nitrogenous wastes are excreted
• Vitamin D necessary for calcium absorption is synthesized in the skin

Thick skin:

1. Give examples of thick skin?
• Palm and sole
2.  Is there any difference in the structure between thick and thin skin?
• There is no difference in the structure, except in the thickness of the epidermis and the appendages. In thick skin only sweat glands are present
3. What are sweat glands?
• Sweat glands are exocrine glands which are simple tubular highly coiled glands.
• coiled secretory portion is lined by simple columnar epithelium
• Ductal excretory portion is lined by stratified cuboidal epithelium
4. Why is epidermis in palm and sole very thick?
• These regions are constantly exposed to wear, tear and abrasion
5. What are the types of cells present in epidermis?
• Keratinocytes
• Melanocytes
• Langerhan's cells
• Merkel's cells
6. What are dermal papillae?
• The numerous raised projections in the superficial layer of dermis which interdigitate with evaginations of epidermis is called dermal papillae
7. What are epidermal ridges?
• The evaginations of epidermis which interdigitate with the dermal papillae are called epidermal ridges
8. What are the two layers of dermis?
• Superficial papillary layer
• Deep reticular layer
9. What is papillary layer made up of?
• It is made up of loose irregular connective tissue with cells and fibers, capillaries, blood vessels, fibroblasts, macrophages, nerves, Meissner's corpuscles
10. What is reticular layer made up of?
• It is made up of dense irregular connective tissue with less number of cells, Pacinian corpuscles
11. What are the layers of epidermis?
• From deep to superficial- Stratum basale (germinativum), stratum spinosum, stratum granulosum, stratum lucidum, stratum corneum
12. Why is stratum basale also called as germinativum?
• The single layer of cuboidal or columnar cells are capable of cell division which increases the number of cells and differentiate into other layers. They act as stem cells and also produce intermediate keratin filaments
13. Explain stratum spinosum?
• It consists of 4 to 6 rows of cells. During routine histologic preparations the cell membranes shrink except near the desmosomes which appear as spines. The keratin filaments are arranged in the form bundles called tonofilaments.
14. Why is third layer given the name stratum granulosum?
• The cells in the third layer are filled with dense basophilic keratohyalin granules which lack membrane and are associated with bundles of keratin filaments, together form keratin. Because of the keratohyalin granules the third layer is called stratum granulosum
15. What is stratum lucidum?
• It is a translucent layer present superficial to stratum granulosum. The cells lack nuclei or orgenelles
16. What is stratum corneum?
• It is the superficial layer of cells without nuclei and organelles, filled with keratin filaments. They are continuously shed or desquamated
17. Where are melanocytes derived from?
• Melanocytes are derived from Neural crest cells
18. Where are melanocytes located?
• They are located between stratum basale and stratum spinosum. The function is to synthesize melanin pigment which protects the skin from damaging effects of ultraviolet radiation

Thin skin:

1. What are the layers present in thin skin?
• Four layers from deep to superficial- stratum basale, stratum spinosum, stratum granulosum, stratum corneum. Stratum lucidum is absent.
• Except the thickness and the absence of stratum lucidum the rest of the features are same as in thick skin
2. Name the appendages of thin skin
• Hair, sebaceous glands, arrector pili muscle, sweat glands
3. What is dermal papillae?
• The papillary layer indents the base of the epidermis to form the dermal papillae
4. What are sebaceous glands?
• Sebaceous glands are exocrine and holocrine glands with aggregates of clear cells connected to duct opening into hair follicle
• It secretes oily or wax material to lubricate and water proof the skin
5. What is holocrine secretion?
• The whole is cell is destroyed during the secretion which is poured into the lumen
6. What are arrector pili muscles?
• Arrector pili muscles are smooth muscles aligned at oblique angle from papillary layer of dermis to the hair follicle
• Contraction of the muscle moves hair shaft into vertical position

Lymph node, spleen, thymus, tonsil- discussion, viva

Lymphatic system:

1. What is the function of lymphatic system?
• The function of lymphatic system is immunity / to protect the organism from invading pathogens or antigens
2. What are the components of lymphatic system?
• Cells- distributed throughout the body as single cells or aggregations of cells or non-encapsulated lymphatic nodules
• Lymphatic organs- lymph node, spleen, thymus, tonsil
3. Name the lymphatic organs surrounded by connective tissue capsule
• Lymph node, spleen, thymus
4. Name the lymphatic organ covered by epithelium
• Tonsil

Lymph node:

1. What are the parts of lymph node?
• Outer cortex- network of reticular fibers, non-encapsulated aggregations of lymphocytes called lymphatic nodules with pale germinal center
• Inner medulla- medullary cords (irregularly arranged lymphocytes, macrophages, plasma cells in network of reticular fibers) and medullary sinuses
2. What is direction of flow of lymph?
• Afferent lymphatic vessel--subcapsular sinus--trabecular sinus--medullary sinus--efferent lymphatic vessel
3. What is the function of lymph node?
• The function of lymph node is to filter the lymph as it enters the lymph node
4. What are lymph sinuses?
• Lymph sinuses are the spaces with fine network of reticular fibers filled with lymph
• Subcapsular sinus- sinus present beneath the connective tissue capsule
• Trabecular sinus- sinus present around the connective tissue septa (trabeculae) entering the lymph node
• Medullary sinus- sinus present in the medulla
5. What are germinal centers?
• The germinal centers are the pale regions in the center of lymphatic nodule which represent the active sites of lymphocyte proliferation

Spleen:

1. What are the parts of spleen and their components?
• Red pulp- splenic cords of Billroth (network of reticular fibers with macrophages, lymphocytes, plasma cells, blood cells) and splenic/blood sinuses
• White pulp- dark staining lymphoid aggregations/nodules surrounding a central artery. Along with lymphocytes, antigen-presenting cells and macrophages are also seen
2. What is the function of red pulp?
• The function of red pulp is to filter the blood. It removes the antigens, microorganisms, platelets and aged or abnormal erythrocytes from the blood.
3. Is there a germinal center in the lymphatic nodule present in spleen?
• Yes
4. What are the types of lymphatic cells seen in white pulp?
• T cells- surround the central arteries
• B cells- present in rest of lymphatic nodule
5. What are the functions of spleen?
• Fetal life- produces granulocytes and erythrocytes
• Important reservoir for blood
• Filters blood
• Takes part in immunity
6. Is spleen essential for life?
• No, it is not

Thymus:

1. Where is thymus located?
• Thymus is located in the root of neck and upper anterior mediastinum
2. What are the stages of thymus?
• Childhood- most active upto puberty
• After puberty- undergoes involution
• Adults- replaced with adipose tissue
3. What are the parts of thymus?
• Connective tissue capsule divides the thymus into incomplete thymic lobules. Each thymic lobule has peripheral cortex and inner medulla which is continuous with adjacent lobules
• Cortex- densely packed lymphocytes
• Medulla- few lymphocytes, more epithelial reticular cells, thymic/Hassall's corpuscles
4. What are Hassall's corpuscles?
• They are oval structures consisting of round or spherical aggregations of flattened epithelial cells around the calcified or degenerating mass of epithelial cells
5. What are the functions of epithelial reticular cells?
• The epithelial reticular cells forms the blood-thymus barrier and secretes hormones necessary for proliferation, differentiation and maturation of T-cells
6. What happens to the child if thymus is removed?
• The child may not be able to fight pathogens and death may occur as a result of infection and lack of functional immune system
7. What are the hormones secreted by epithelial reticular cells?
• Thymulin, thymopoietin, thymosin, thymic humoral factor, interleukins, interferon
8. Name the layers forming blood-thymic barrier?
• Endothelial cells
• Epithelial reticular cell
• Macrophages

Tonsil:

1. Where is tonsil located?
• Tonsil is located at the oro-pharyngeal isthmus on either side of oral cavity
2. What are the parts of tonsil?
• Attached surface- covered by connective tissue capsule
• Free surface- covered by stratified squamous non-keratinized epithelium which invaginates into the tonsil as tonsillar crypts
• Tonsillar crypts are surrounded by numerous lymphatic nodules