David Barlow's video: Mast Cells

Mast cells are present in most tissues of the body. Their coarse structure of the cell is due to the presence of many granules containing compounds such as Histamine. Histamine is important to stimulate the mounting of a proper immune reaction at the site of an injury. Its presence causes capillaries to become more permeable, releasing proteins into the area of infection and attracting other immune cells such as macrophages that can fight the infection. If the immune response becomes overactive such as with allergies, then Mast cell de-granulation of histamine can cause excessive reactions such as in anaphylaxis. In asthma, histamine can cause the smooth muscle in the walls of bronchial tubes to contract, narrowing the airways. These clips can be found in the film archive at: http://www.davidbarlowarchive.com/categories/microscopy/mast-cells.html