Capsule

CAPSULE (Lat. capsula), a term used in normal and pathological anatomy to denote the membranes that envelop and separate various organs or their parts, or finally border certain pathological formations that arise in tissues and organs. Thus, anatomists speak of the capsule of the spleen, adrenal glands, the fatty capsule of the kidney, Bowman's capsule surrounding the Malpighian corpuscles of the kidneys, the inner and outer capsules in the area of the cerebral hemispheres, the joint capsule, etc. From these examples it follows that in normal anatomy there is no definite structure of the capsule; being in most cases fibrous connective tissue formations, sometimes with an admixture of smooth and elastic fibers, capsules sometimes consist of fatty tissue and

nerve fibers. Often along with the term capsule, the terms membrane, sac, tunica are used. In pathology, capsules are newly formed inflammatory membranes that primarily consist of granulation tissue, and later of dense fibrous or scar tissue; such capsules can subsequently undergo transformations (metaplasia) into cartilaginous or bony capsules. The cause for the development of capsules in pathology is various foreign bodies penetrating into tissues or forming within them, such as: shrapnel fragments, parasites, necrotic masses, pigments, etc. The process of capsule development around various pathological formations or foreign bodies is called encapsulation. A special type of capsule is meant when speaking of capsule bacteria (see).