The material within the cyst is produced by the cells that make up the lining, or wall, of the cyst.
Some cysts form during development of the embryo but the majority form later in life.
Causes Cysts form for a variety of reasons, depending to some degree on the tissue involved. Hormones are believed to play a role in the formation of cysts of the breast. Some cysts that form in the adrenal glands are caused by bacterial infections or by parasites. The cause of other cysts is unknown. Incidence Many people develop cysts.