Substances that consist of glycol groups or alkylamino and amino derivatives are normally oxidized to form. An insoluble pink/magenta chromogen is later formed after these dialdehydes Periodic acid combines with the Schiff’s reagent. In tissue sections PAS positive substances include: Amyloid, cartilage, collagen, mucins, glycogen, and basement membranes among others, together with some organisms such as fungi.
Most carbohydrates are broken down by the body from the foods we eat; it is further converted to a sugar type referred to as glucose. The main fuel source for the cells is glucose. When glucose is no longer needed by the body for energy, it is stored in the muscles and liver. The glucose stored consists of many connected glucose molecules referred to as glycogen. When a quick energy boost is required by the body in cases where the body is not receiving any glucose from food, there is break down of glycogen that results to glucose release into the bloodstream to generate fuel for the cells.( Knebelmann et al,1996)
Glycogen demonstration in tissue sections, for example for the liver section tissues, it can be used to differentiate between normal liver tissue and the abnormal liver tissue by looking at the morphology. The liver is the main organ that stores glycogen. Any observation made after staining of the liver tissue that is different from typical liver tissue staining will indicate that the tissue is not normal hence diseased. For example, liver and fatty liver cells, scar tissue (fibroblasts) can be used to differentiate between normal and abnormal liver tissues( hepatocytes) after staining because of the absence of glycogen in normal cells. The diastase use in enzymes digestion of glycogen acts as a control. Hence, two slides comparison can show an area occupied by glycogen. PAS Stains glycogen but there can be pre-digestion of tissue with diastase in order to remove glycogen.
At least 10 different GSDs types do exist. These