Lab 21 Liver, Gall Bladder, Pancreas: 1) Index 2) Introduction 3) Things to Identify 4) The Liver 5)Gall Bladder 6) Cystic Duct 7) Pancreas 8) Practical

 

The Pancreas

 

# 217 - Pancreas, rabbit, 1.5 mm, h-e

# 137 - Pancreas, monkey, Mallory

*If needed, # 136 - Pancreas, monkey, h - e

 

The parenchyma of the exocrine pancreas is composed largely of dark-staining serous cells arranged in acini. Interspersed among these acini is the endocrine component of the pancreas, spherical aggregations of lighter staining cells called the islets of Langerhans.

Identify: 1) an acinus of serous cells, 2) pale-staining centroacinar cells present within the pancreatic acini, and 3) intercalated (intralobular) ducts and 4) interlobular ducts. This organ histologically resembles some salivary glands (especially the parotid) except for the presence of the islets of Langerhans and the absence of striated intralobular ducts.

Centroacinar cells have a pale staining cytoplasm that contrasts with the basophilic cytoplasm of the parenchymal acinar cells which secrete enzymes and have a high RER content.

REFERENCES: Ross, pp. 528 - 529; pp. 514 - 517 Gartner, pp. 300, 304-305, Fig. 1 DiFiore, p. 225, Fig. 14.10 - 14.12 Wheater, p. 279 - 280, Fig. 15.3 - 15.4

 

This is a low power image of the Pancreas. The liver is made up of two parts, Exocrine Pancreas made up of Secretory Acini and the Endocrine Pancreas made up of Islets of Langerhans indicated by the white arrows. These have a lighter staining pattern and stick out against the darker staining pattern of the acini.

White arrows - Islets of Langerhans

 

Here is a closer look at the difference between the Exocrine & Endocrine pancreas. The Red arrow is pointing to the light staining Islets of Langerhans while the yellow dotted lines are outlining the dark staining Secretory Acini. The secretory acini of the pancreas have a very characteristic cell type that give it away called Central Acinar Cells, indicated by the white arrows. These cells are very light staining and located with in the acini which make them stand out. These give away the fact that you are in the pancreas. Also located with in the exocrine pancreas are Intercalated Ducts indicated by the green arrow. There are no STRIATED DUCTS located in the pancreas.

Red arrow - Islet of Langerhan

Green arrow - Striated duct

Yellow dotted lines - Secretory Acini

White arrows - Central Acinar Cells

 

Here is a closer look at the Islet of Langerhans. These are made of specialized cells like Alpha cells (blue arrows) which make and secrete glucagon are located at the periphery of the islets while the Beta cells who make and secrete insulin (red arrows) are located in the center of the islets. The white arrows are pointing to the Acinar Cells of near by acini. Notice how much darker these cells are than the cells of the islet.

White arrows - Acinar Cells

Red arrows - Beta Islet Cells

Blue arrow - Alpha Islet cells

 

 

 

Here is another look at the Exocrine Pancreas and the Acini (white dotted lines) which make it up. The yellow arrows are pointing to the characteristic Central Acinar cells which are the Key to identifying the pancreas. Notice how they stand out against the dark cells of the acini.

White dotted lines - Pancreas Acini

Yellow arrows - Central Acinar Cells

 

 

 

 

 

 

Here is a closer look at the make up of the Acini of the pancreas. The red arrow is pointing to a Intercalated Duct. REMEMBER there are no Striated ducts in the pancreas. The blue arrows are pointing to the Acinar cells. At this magnification you can make out the red granules that make them up. The yellow arrows are pointing to the light staining Central Acinar Cells which are located with in the Acini.

Blue arrows - Acinar Cells

Yellow arrows - Central Acinar Cells

Red arrow - Intercalated duct

Pancreas (islets of langerhan)

Pancreas (acini & islets)

Islet of Langerhans

Pancreas Acini

Central Acinar Cells