Secretory Mechanisms
The secretory cells can release their secretory
products by one of three mechanisms.
 
  | 
 | 
Merocrine
  secretion 
corresponds to
  the process of exocytosis. Vesicles open onto the surface of the cell, and
  the secretory product is discharged from the cell without any further loss of
  cell substance. | 
  | 
Apocrine secretion 
designates a
  mechanism in which part of the apical cytoplasm of the cells is lost together
  with the secretory product. The continuity of the plasma membrane is restored
  by the fusion of the broken edges of the membrane, and the cell is able to accumulate
  the secretory product anew. This mechanism is used by apocrine sweat glands,
  the mammary glands and the prostate. | 
  | 
 | 
Holocrine 
secretion designates the breakdown and discharge of
  the entire secretory cell. It is only seen in the sebaceous glands of the
  skin. | 
There are two additional
mechanisms by which secretory cells can release their products. Lipid soluble
substances may diffuse out of the secretory cell (e.g. steroid
hormone-producing endocrine cells). Transporters (membrane proteins) may
actively move the secretory product across the plasma membrane (e.g. the acid
producing parietal cells of the gastric glands). These secretory mechanisms may
not involve any light microscopically visible specialisations of the cell.
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Title: 
Secretory Mechanisms
by:
om
at 
2013-02-15T02:48:00+07:00
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Secretory Mechanisms