Image: Thymus Gland

Thymus Gland

Thymus Gland, endocrine gland that serves an important role in the body`s immune system. It stimulates the development of T (thymus) cells both within the thymus itself and within lymphoid tissue elsewhere in the body. T cells attack foreign substances invading the body. They also exert control over the production of disease-fighting antibodies by other cells of the immune system and influence other protective reactions.

The thymus is found in all vertebrates

The thymus is found in all vertebrates, but its shape and location vary. In humans, the thymus consists of two lobes located in the upper chest immediately behind the top of the breastbone. In reptiles and birds, the thymus usually occurs as two lobular chains strung out along each side of the neck.

The thymus gland consists chiefly of lymphatic

The thymus gland consists chiefly of lymphatic tissue and contains a few small areas of epithelial tissue known as Hassall`s corpuscles. The human thymus gland increases in weight in the first two years of life, and from then until puberty it grows slowly to a weight of about 43 g (about 1.5 oz). After puberty, it shrinks gradually and the lymphatic tissue of the thymus gland is replaced by fat. In the adult human the organ is chiefly composed of fatty tissue. Abnormal enlargement of the thymus or development of tumors of the gland may occur in myasthenia gravis.

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