1. Secretion

2. Secretion Not visible in LM sections Visible in LM sections
In constitutive secretory pathway
secretory vesicles DO NOT accumulate
eg. extracellular matrix
Membrane replacement
or exocytosis
All cells, continuously
Not visible in LM sections
signal
In regulated secretory pathway
secretory vesicles
accumulate in glandular cells
or exocytosis
Hormone, digestive enzymes
or neurotransmitter
Visible in LM sections
Glandular cells and neurons

3. Note the differences:
Secretion: synthesis, modification and release of different substances having physiological function
Excretion: Discharging waste matter
Common step: exocytosis: fusion of the membrane of a vesicle and the plasma membrane thus release of vesicle content outside of the cell

4. Grouping of glands According to the: Size: unicellular - multicellular
Site where the substances are secreted to: exocrine – endocrine
Mechanism of release: merocrine,
holocrine,
apocrine
Cell polarity : polarized
not polarized
Secreted substances : proteins
highly glycosylated proteins
biogenic amines
proteoglycans
steroids
etc.

5. Cell polarity Mast cell - Non-polarized Goblet cell - polarized

6. Secreted substances

7. Protein secreting cell
Plasma cell (unicellular)

8. Protein secreting cell
Exocrine pancreatic acinar cell (multicellular gland, polarized cell)
Basic Histology 7.ed.
Polarized cytoplasmic basophilia

9. Protein secreting cell
Exocrine pancreatic acinar cell (multicellular gland, polarized cell)
Condensation
(Water loss)

10. Highly glycosylated protein = glycoprotein (mucus) secreting cell
Goblet cell (unicellular, polarized)
Hydration
(water uptake)

11. Biogenic amine and proteoglycan secreting cell
Any of a group of naturally occurring, biologically active amines, such as norepinephrine, histamine, and serotonin, that act primarily as neurotransmitters and are capable of affecting mental functioning and of regulating blood pressure, body temperature, and other bodily processes.
accumulation
degranulation

12. Steroid hormone secreting cell
Features
A lot of SER
Lipid droplets
Tubular mitochondria

13. Steroid hormone secreting cell

14. Slide

15. Slide No. 11. Rat peritoneal fluid, thick-drop (toluidine blue)
1: mast cells: (metachromasia due
to heparin content)
Accumulation and degranulation
2: lymphocyte
degranulation
accumulation

16. Slide No. 11. Rat peritoneal fluid, thick-drop (toluidine blue)
Mast cell during degranulation
1: nucleus of mast cell

17. Facultative

18. Secretion or exocytosis or exocytosis All cells, continuously signal
eg. extracellular matrix
Membrane replacement
or exocytosis
All cells, continuously
signal
or exocytosis
Hormone, digestive enzyme
or neurotransmitter
Glandular cells and neurons

19. Mechanism of release (types of glands)
Merocrine
E.g. exocrine part
of pancreas
Apocrine
E.g. Mammary gland
Some sweat glands
Holocrine
Eg. Sebaceous gland