Changes

===Endocrine===

===Endocrine===

[[Image:Islet cell types.jpg|thumb|right|150px|Islet of Langerhans - © RVC 2008]]

[[Image:Islet cell types.jpg|thumb|right|250px|Islet of Langerhans - © RVC 2008]]

*Islets of Langerhans are embedded in the exocrine tissue.

In the endocrine pancreas, the '''islets of Langerhans''' are embedded in the exocrine tissue. Each islet is composed of 2 - 3 thousand epithelial cells. The epithelial cells are arranged in a compact structure that is pervaded by a capillary network. A thin layer of reticular fibres seperates the islets from the surrounding exocrine tissue. There are ''four'' different cell types within the islets of Langerhans that each produce different hormones, they include:

*Each islet is composed of 2 - 3 thousand epithelial cells.

 

*Epithelial cells are arranged in a compact structure that is pervaded by a capillary network.

'''1. α cells'''- Produce glucagon, typically located at the periphery of the islet. They are not present in all islets.

*A thin layer of reticular fibres seperates the islets from surrounding exocrine tissue.

 

*There are ''four'' different cell types within the islets of Langerhans that each produce different hormones.

'''2. β cells'''- Produce insulin. The predominant cell type, located in the centre of the islet and contributing to 70% of all cells.

**α cells produce glucagon. Typically located at the periphery of the islet. Not present in all islets.

 

**β cells produce insulin. The predominant cell type, located in the centre of the islet and contributing to 70% of all cells.

'''3. δ cells'''- Produce somatostatin. There are low numbers in all islets.

**δ cells produce somatostatin. Low numbers in all islets.

 

**F cells produce pancreatic polypeptide and are few in number, and may be present in the exocrine tissue also.

'''4. F cells'''- Produce pancreatic polypeptide and are few in number, they may be present in the exocrine tissue also.

==Species Differences==

==Species Differences==