Histology of glands

Hello friends..you can use these notes for your convenience as they are taken from many other standard books.. Thank you.

1. HISTOLOGY OF GLANDULAR TISSUE By- Dr Vibhash K. Vaidya Department of anatomy

2. Learning objective - Introduction of gland Development Types of glands Unicellular gland Multicellular gland Classification of multicellular gland

3. Glands Secretory cells derived from epithelia get organised along with supportive tissue to from a gland. Gland can be exocrine or endocrine . Exocrine glands release their secretory product directly on the surface. Endocrine glands release their secretory product diffuses into the bloodstream.

4. Development Both end & exocrine gland are derived from surface epithelium. Epithelial cells multiply and extend into the underlying connective tissue and form glands. The exocrine glands retain the connection with the surface epithelium through their ducts. Whereas in endocrine gland this connection is lost.

5. EXOCRINE GLANDS Structurally exocrine glands may exist in a very simple form such as a single cell functioning as a gland and releasing its secretion on the surface. Alternately, they may also exist as multiple secretory cells ( along with non-secretory cells) which form a complex structure. The secretory product of such complex glands is conveyed by ducts which open on the surface. All exocrine glands can be broadly classified into two groups, unicellular and multicellular glands.

6. Unicellular glands - as the name suggests, these are glands consisting of single cells. The only example for this type of gland is a goblet cell, which secretes mucus. Multicellular glands - These glands consist of many secretory cells. Most of the exocrine glands are multicellular glands. They have duct which convey their secretory product to the surface.

7. CLASSIFICATION OF MULTICELLULAR EXOCRINE GLANDS Secretory part can be tubular , acinar , coiled or branched (simple branched tubular)

8. Simple tubular gland - the duct is unbranched and secretory unit is tubular in shape. Example- section of intestine showing intestinal gland.

9. Simple coiled tubular gland - the duct is unbranched and secretory unit is tubular in shape with coiling. Example- section of skin showing sweat glands

10. Simple branched tubular gland - the duct is unbranched and secretory unit is tubular in shape and branched. Example- section of stomach showing gastric glands

11. Simple branched acinar gland - the duct is unbranched and secretory unit is acinar in shape and branched. Example- section of skin showing sebaceous glands

12. Compound tubular gland - the duct is branched and secretory unit is tubular in shape. Example- section of duodenum showing Brunner's glands.

13. Compound acinar gland - the duct is branched and secretory unit is acinar in shape. Example- exocrine part of pancreas.

14. Compound tubuloacinar gland - the duct is branched and secretory unit is tubuloacinar in shape. Example- submandibular salivary gland

15. Merocrine or eccrine gland - Secretory vesicles open onto the surface of the cell. Secretory product is discharged (exocytosis) from the cell without any loss of cell substance. Example- acinar cells of pancrease and goblet cell.

16. Apocrine gland Part of the apical cytoplasm of the cells is lost along with the secretory product. Example- mammary glands and apocrine sweat glands.

17. Holocrine gland The plasma membrane of the secretory cell breaks down and releases its secretion and the cell dies. The lost cell is replaced by a new cell. Example- sebaceous glands.

18. Serous acini Cells of serous acini are triangular in shape with round nuclei at their bases. Apical cytoplasm is eosinophilic and cytoplasm at the base is basophilic. The luman of these acini is small. Secretion are watery. Mucous acini Cells are tall with flat nuclei at the bases. The luman of these acini is large than serous acini . Secretion of mucus acini is thick.

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