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Stellate cells are star-shaped neurons and astrocytes. These cells contain several dendrites that radiate from the cell body, thus giving these cells an unusual appearance. There are several different types of stellate cells, with the most common being located in the cerebellum portion of the brain. The cerebellar stellate cells pass onto neurons known as Purkinje cells.
Purkinje cells belong to a class of neurons located in the cerebellar cortex. The name of these cells originate from the Czech anatomist responsible for its discovery, Jan Evangelista Purkyně. Purkinje cells are among the largest neurons present in the human brain. They are responsible for motor coordination in the cerebellar cortex.
The Purkinje cells are stacked in front of each other, causing them to have a domino-like appearance. There are many parallel fibers passing through the dendritic arbor of the Purkinje neuron. However, each of these neurons comes together from just only a single climbing fiber. These cells are capable of switching back and forth between quiet and active states.
Several diseases or conditions are prone to causing damage to the Purkinje cells. A common cause for this damage is alcohol or lithium use. Autoimmune diseases and genetic mutations, including autism, may also lead to damage involving these cells. There have also been reports of damage due to neurodegenerative diseases, which have no known genetic basis. These can include conditions such as multiple system atrophy or sporadic ataxias.
Hepatic stellate cells, also known as ito cells, are located in the liver. In a normal liver, the hepatic stellate cells do not move, although the reason for this is not completely understood. When damage to the liver occurs, these stellate cells begin to contract and proliferate. For example, in the case of fibrosis, a condition involving scar tissue formation in the liver, the hepatic stellate cells are the primary cells affected by the disease. In some cases, cirrhosis of the liver can be caused when the activated stellate cell secretes collagen scar tissue into the liver.
Much like the hepatic stellate cells of the liver, the pancreatic stellate cells are capable of switching from a dormant state to one of activation. These cells are located in the exocrine areas of the pancreas. Once the pancreatic stellate cells become activated, they migrate to the area of injury in order to aid in tissue repair. As such, these cells may play a vital role in the pathogenesis of conditions such as pancreatitis and pancreatic cancer.