Effects of Mast-Cell Degranulation on the Choroid

The mast cells have been an object of study since they were first described by Ehrlich in 1879. Although there is variation among species, these cells have been seen most commonly along blood vessels, in organ capsules, and floating free in the peritoneal cavity. They are generally associated with the connective tissue, are abundant in skin, and scarce in neural tissue. Until recently, knowledge of mast cells in the eye has been scant. In 1937 Jorpes1first observed mast cells at the limbus in human and bovine corneas. More recently, Smelser and Silver2found many mast cells in the limbus and choroid of guinea pigs, rats, and rabbits. Mast cells are easily missed in routine histologic preparations because they are destroyed by aqueous fixatives and do not show differential staining with hematoxylin and eosin. A typical tissue mast cell is 1020μ in diameter.3,4When stained with toluidine