1. Histology of Glands 12.02.2015 Dr. Archana Rani Associate Professor
Department of Anatomy
KGMU UP, Lucknow

2. Introduction
A gland is an organ that consists of specialized secretory cells.
Secreted material is usually a liquid.
Epithelial in origin.
Present in singly or in groups.
Unicellular or Multicellular
2 types:
Exocrine
Endocrine

3. Unicellular glands Single cell distributed among non-secretory cells.

4. Multicellular glands
Formed by invagination of epithelial layer in deeper tissue to form a diverticulum:
Proximal part forms duct.
Distal part forms secretory element.

5. Endocrine (ductless): pour their secretions directly into the blood.
Exocrine: pour their secretions onto an epithelial surface, directly or through ducts.
Endocrine (ductless): pour their secretions directly into the blood.

6. Classification of exocrine glands
Based on shape & branching pattern of duct
Based on mode of release of their product
Based on the nature of their secretion

7. Classification based on shape & branching pattern of duct
Based on shape of secretory units (tubular or alveolar) & branching pattern of ducts.
2 types:
Simple Compound

8. Contd… Simple glands: Compound glands: Simple tubular Compound tubular
Simple coiled tubular
Simple branched tubular
Simple branched alveolar
Compound glands:
Compound tubular
Compound alveolar
Compound tubulo-
alveolar

9. Simple glands

10. Compound glands

11. Sweat glands
Fundic glands of stomach
Meibomian glands
Crypt of Lieberkuhn
Brunner glands
Submandibular gland
Mammary gland

12. Classification based on mode of secretion
Merocrine: secretion is released by exocytosis of secretory granules (pancreas, parotid gland, protein component of milk from mammary gland).
Apocrine: apical portion of cell along with secretory product is pinched off (lipid component of milk from the mammary gland).
Holocrine: entire cell is shed along with secretory product (sebaceous glands).

13. Modes of secretion

14. Modes of secretion Merocrine

15. Modes of secretion Merocrine: secretion by exocytosis

16. Modes of secretion Merocrine: secretion by exocytosis Apocrine

17. Merocrine: secretion by exocytosis
Modes of secretion
Merocrine: secretion by exocytosis
Apocrine: secretion by loss of cytoplasm

18. Merocrine: secretion by exocytosis
Modes of secretion
Merocrine: secretion by exocytosis
Apocrine: secretion by loss of cytoplasm
Holocrine

19. Merocrine: secretion by exocytosis
Modes of secretion
Merocrine: secretion by exocytosis
Apocrine: secretion by loss of cytoplasm
Holocrine: secretion through loss of entire cell

20. Classification based on the nature of secretion
Serous glands
Mucous glands
Mixed glands

21. Serous glands
Secretion: thin, watery, rich in enzymes, protein in nature.
Cytoplasm: granular (stain darkly from pink to dark purple with H/E stain) & rich in rER.
Nuclei: rounded & basally placed.

22. Mucous glands
Secretion: contains mucopolysaccharides which collects in the apical part of cell.
Cytoplasm: stain very lightly with H/E stain & therefore gives empty look.
Nuclei: basally placed & flattened (mucoid pushes the nuclei).

23. Mixed glands Contain both serous & mucous secretory units.
Sometimes serous cells form crescentic caps on mucous acini called as serous demilunes.

24. Salivary glands

26. Major glands
Lie completely outside the alimentary tract & connected to it by an excretory duct.
Compound alveolar or tubuloalveolar in type.
Parotid, submandibular, sublingual.

27. Minor glands Small salivary glands situated in the mucous membrane of:
Lip (labial)
Cheeks (buccal)
Soft palate (palatine)
Tongue (lingual)

28. Functions of Salivary glands
Secrete saliva composed of water, mucus, proteins, salts, salivary amylase (ptyalin), immunoglobulins (IgA) & lactoperoxidase.
Serves to moisten food.
Lubricates & moistens oral mucosa and lip.
Initiates the digestion of carbohydrates.

29. Basic organization

30. Different types of acini
Mucous Serous Mixed

31. Features of serous & mucous cells
Serous cell
Mucous cell EM LM

32. Differences between serous & mucous acini

33. Differences between serous & mucous cells

34. Parotid gland

35. Submandibular gland

36. Sublingual gland

39. References
1. diFiore’s Atlas of Histology with functional Correlations, 12th Edition.
2. Textbook of Human Histology. Inderbir Singh, 1st Edition.
3. Textbook of Histology. GP Pal, 3rd Edition.

40. MCQ
1. All are major salivary glands except: a) Palatine b) Parotid c) Submandibular d) Sublingual

41. MCQ
2. Holocrine type of secretion is a feature of: a) Mammary gland b) Parotid gland c) Sebaceous gland d) Pancreas

42. MCQ
3. Sweat gland is an example of: a) Simple tubular gland b) Simple coiled tubular gland c) Simple branched tubular gland d) Simple alveolar gland

43. MCQ
4. All are true about serous acini except: a) Smaller in size b) Stain dark c) May present as demilune d) Wide lumen

44. MCQ
5. Expelling of secretion through contraction is a feature of: a) Serous cell b) Mucous cell c) Serous demilune d) Myoepithelial cell