Liver, Gall Bladder, and Pancreas

Liver

Human liver
The principal parenchymal cell is the hepatocyte. Some hepatocytes are binucleate. The connective tissue present is mostly seen at the border regions between classic liver lobules. Note the connective tissue covering the uncut surfaces of this section. This is Glisson's capsule. Observe how the connective tissue septae dividing the lobules are continuous with the capsule.
You can easily observe the components of the classic lobule on this specimen. Find central veins and identify the plates (or cords) of hepatic cells that radiate out from the central vein. These cords of hepatic cells are separated by sinusoids. At the six apices of the classic lobule, observe the portal triads made up of hepatic artery, portal vein, bile duct, and lymphatic vessels. The lymphatic vessels are not visible in this preparation. Also locate sublobular veins which are found separate from the hepatic (portal) artery, portal vein, and bile duct. Sublobular veins coalesce into the hepatic vein which carries blood from the liver to the vena cava.
In addition to the classic liver lobule you should also envision the portal lobule and the liver acinus.

Liver,1.5 mm, monkey
Observe the portal triads made up of hepatic artery, portal vein, bile duct, and lymphatic vessels. Observe the finer details of the hepatocytes, the space of Disse, and Kupffer cells.

Liver, PAS and H&E
Kupffer cells are seen best in this specimen. Recall that these cells are macrophages and contain particulate matter. Also observe the space of Disse, which is the thin perisinusoidal space between hepatocytes and endothelial cells.

Liver, Van Gieson and silver stain
In this specimen, reticular fibers and collagen fibers have been stained. Note the extensive network of reticular fibers which literally cradle the liver cells. Compare the distribution of collagen and reticular fibers.

Gall Bladder

Gall bladder, monkey
The gall bladder functions to concentrate and store bile. It is a hollow, pear shaped organ with walls composed of three layers: a mucosa, muscularis externa, and adventitia (serosa). Note that the orientation of the smooth muscle in the muscularis externa is somewhat random. Notice the very tall, simple columnar epithelium of the mucosa which is thrown into numerous villus-like folds. The lamina propria of the mucosa is highly vascular with no lymphatics. No muscularis mucosa or submucosa exists in the gall bladder.

Exocrine Pancreas

Pancreas
The exocrine component of the pancreas is a compound tubuloacinar gland with a complex series of ducts that convey the exocrine secretion of the pancreas to the duodenum. Observe the serous acini of the pancreas. Each acinus is composed of acinar cells. Note the basophilia in the basal portion of the acinar cells and eosinophilia of the apical portion. Some acini reveal the centrally located centroacinar cells. These cells are the beginning of intercalated ducts lined with a simple low columnar or cuboidal epithelium. The intercalated ducts empty into the intralobular ducts which have a cuboidal epithelium. These ducts empty into the interlobular ducts which run within the connective tissue septa dividing the pancreas into lobules. The interlobular ducts coalesce to form the pancreatic duct which empties into the duodenum.
The endocrine portions of the pancreas are the islets of Langerhans and are seen as islands of pale-staining cells spread through the organ. Defer your detailed study of these until the endocrine glands are covered in the endocrine system laboratory.
Note: the pancreas can be distinguished from the parotid gland in that the pancreas does not have striated ducts, and the pancreas has the characteristic islets of Langerhans.

Pancreas, 1.5 mm, human
Observe the characteristic features of the exocrine pancreas: serous acini, acinar cells, centroacinar cells, intercalated ducts, intralobular ducts, and interlobular ducts. Note the intense basophilia in the basal portion of the acinar cells and eosinophilia of the apical portion.