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histology_glands_5-2-15.pptx
- 1. Histology of SalivaryGlands
- 4. What is agland? Gland is an organ of secretion made up of specialized secretory cells derived from the surface epithelium on which it opens.
- 5. General Features • Epithelialin origin • Present as discrete organs or in layers. • Secretory cells form functional units called secretory end pieces- may be flask (Acinus)or cylindrical (Tubular)shaped
- 6. Types of Secretoryunits
- 7. General Features • Fluidsecreted may be enzymes, hormones or mucus. • Secretion is modulated by nervous and hormonal influences. • Myoepithelial cells- star shaped, contractile, lie between the secretory cells and the basement membrane
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- 9. Development • Develop asinvagination of the epithelium into the underlying vascular connective tissue. • Distal part forms glandular or Secretory end Piece – functionally an active portion. • Proximal part-Excretory Duct-opens on the surface of the epithelium • Some cells get detached from the epithelial surface- Ductless or endocrine glands
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- 15. Classification of Glands Basedon the site of Secretion • Exocrine Gland • Endocrine Gland • Paracrine Gland- secretes its products into the local extracellular space affecting the surrounding cells e.g. enteroendocrine cells of gastrointestinal tract (GIT)
- 17. Classification of Glands •Based on the Number of cells • Unicellular Gland- goblet cells in the respiratory and intestinal tracts • Multicellular Gland- all glands other than goblet cells
- 18. Classification of Glands Basedon the Number of Ducts and the shape of secretory end piece • Simple Gland- one duct • Compound Gland- has minor and major ducts Both the types are further subdivided into • Tubulo, Alveolar/Acinar or • Tubulo-alveolar/acinous
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- 23. Compound Glands • SimpleAlveolar-Penile urethra • Simple Branched alveolar-Sebaceous gland • Compound Alveolar- Pancreas, Parotid, Mammary gland and glands of Respiratory tract. • Simple Tubular-Crypts of Leiberkuhn • Simple branched tubular-Uterine glands,Pyloric and fundic glands • Compound Tubular-Brunner’s Gland, Cardiac glands • Simple coiled tubular-Sweat gland • Compound Tubulo-alveolar- Submandibular & Sublingual salivary glands
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- 25. Classification of Glands Basedon the Mode of Secretion • Merocrine Gland- No loss of Cytoplasm-e.g. most of the compound glands e.g. Pancreas Also known as Eccrine or Epicrine • Apocrine Gland- Partial loss of cytoplasm-e.g. lactating mammary gland, sweat glands in the axilla and external genitalia • Holocrine Gland- Complete loss of cytoplasm e.g. sebaceous and tarsal gland • Cytocrine Gland- Cells are released as secretion. e.g. Testis (spermatozoa)
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- 27. Classification of Glands Basedon the Nature of Secretion • Serous Gland- thin, watery secretion rich in enzymes e.g. Parotid gland • Mucous Gland- thick, viscous secretion for protection and lubrication. e.g. Sublingual salivary gland • Mixed Gland (seromucous)- both watery and viscous material.e.g. Submandibular salivary gland
- 28. Difference between Serous& Mucous Acini Serous • Thin, watery • Proteinaceous secretion • Zymogen granules in cyto • Central rounded Nucleus • Small Lumen • Indistinct cell bondaries • Darkly stained • Enzymatic action • Parotid Gland Mucous • Thick, viscous • Mucopolysaccharides • Mucigen droplets • Nucleus-flat & peripheral • Large Lumen • Distinct cell boundaries • Lighly stained • Protection & lubrication • Sublingual gland
- 29. Mixed salivary gland •Serous Acini • Mucous Acini • Seromucous Acini- having Serous demilunes
- 32. General Architecture ofa Compound Gland Gland may be divided into lobes and lobules. Parenchyma- • Secretory end pieces- Acini/tubules /tubulo- acinar) • Ducts- Intralobular, interlobular, main excretory duct Stroma • Capsule • Septa (interlobular, interlobar) • Loose intralobular connective tissue supporting the parenchyma
- 33. Clinical • ADENOMA: Benigntumors arising in the gland • ADENOCARCINOMA: Malignant growth in the gland
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- 38. Intra-glandular adipose tissuein parotid gland
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- 47. Minor salivary glandsof Palate • Aggregations of Mucous acini • No striated duct
- 48. Minor salivary glandsof Palate(High Power) • Mucous acini with central Lumen • Large Pyramidal cells with granular cytoplasm • Nucleus towards the basement membrane
- 49. The minor salivaryglands are small aggregates of unencapsulated mucous or serous glands. In the tongue they are in intimate contact with the striated muscle tissue.
- 50. Keratin cocktail stainsintercalated, striated and interlobular ducts, but acinar and myoepithelial cells are mostly negative.
- 51. MCQ • The serousgland can be identified by the presence of serous acinus with • A) Small Lumen • B)Large Lumen • C)Flat peripheral Nuclei • D)Mucigen droplets
- 52. MCQ • When thereis a complete loss of cytoplasm resulting in cell death of the secretory cell during the process of secretion, the gland is said to be • A) Merocrine • B) Apocrine • C) Holocrine • D) Cytocrine
- 53. MCQ Sebaceous gland isan example of • Holocrine gland • Apocrine gland • Merocrine gland • Unicellular gland
- 54. MCQ • Mucous Acinus •A) Secretes thin watery fluid • B) Has flat, peripheral nucleus • C) Has a small lumen • D) Contains zymogen granules
- 55. MCQ • Sweat glandsin the axilla are an example of • A) Merocrine gland • B) Apocrine gland • C) Holocrine gland • D) Cytocrine gland