Though the thymus is a little-known organ in the body,it does some very important things.It is part of the lymphatic system,除了扁桃体，腺样体和脾脏，and it's also part of the endocrine system.
The thymus produces progenitor cells,which mature into T-cells (thymus-derived cells).The body uses T-cells help destroy infected or cancerous cells.T-cells created by the thymus also help other organs in the immune system grow properly.
These cells are so vital,they are often donated to those in need."It (the thymus) is the primary donor of cells for the lymphatic system,much as bone marrow is the cell donor for the cardiovascular system,"according to a paper,""The Thymus: A Forgotten,But Very Important Organ,"published by the U.S.国家医学图书馆（NLM）。
Size & shape
The thymus is located just below the breast bone.It is relatively large in infants and grows until puberty.In adulthood,it starts to slowly shrink and become replaced by fat,according to the National Institute of Neurological Disorders and Stroke.It can weigh only 5 grams in elderly adults.
As it grows smaller,it seems the organ becomes less important."Removal of the organ in the adult has little effect,but when the thymus is removed in the newborn,T-cells in the blood and lymphoid tissue are depleted,and failure of the immune system causes a gradual,fatal wasting disease,"according to Encyclopedia Britannica.
The thymus gets its name from its silhouette.It is shaped much like a thyme leaf,a common cooking herb.It has two separate lobes divided by a central medulla and a peripheral cortex and is 澳门金莎网上游戏formed with lymphocytes and reticular cells.The reticular cells 澳门金莎网上游戏form a mesh that is filled with lymphocytes.
Diseases & conditions
Themost common thymus diseasesare myasthenia gravis (MG),纯红细胞再生障碍（prca）和低丙种球蛋白血症，according to the NLM.
Myasthenia gravis occurs when the thymus is abnormally large and produces antibodies that block or destroy the muscles' receptor sites.This causes the muscles to become weak and easily tired.
可能会开一些药物来帮助神经和肌肉之间的沟通，such as pyridostigmine (Mestinon).Corticosteroids like prednisone or immunosuppressants,such as azathioprine (Imuran),mycophenolate mofetil (CellCept),cyclosporine (Sandimmune,Neoral),甲氨蝶呤（trexall）或他克莫司（prograf）may be used to inhibit the immune system.Your doctor may also prescribe other medications that alter your immune system,according to theMayo Clinic.
Pure red cell aplasia is thought to be caused commonly by the patient's own immune cells attacking blood-澳门金莎网上游戏forming stem cells.当胸腺有肿瘤时会发生这种情况，according toThe Aplastic Anemia and MDS International Foundation.Blood transfusions to increase red blood cell levels,corticosteroids and immunosuppressive therapy can all be treatments for this condition.
Hypogammaglobulinemia is a disorder where the body doesn't produce enough antibodies.Infants with this condition typically grow out of it without medical intervention.
Thymus cancer is a disease in the thymus,rather than one caused by the thymus,like the previous examples.Symptoms may include shortness of breath,cough (which may bring up bloody sputum),胸痛，吞咽困难，食欲不振和体重减轻，headaches,swelling of head face or neck,皮肤发青，头晕，according to theAmerican Cancer Society.Thymus cancer is treated with surgery,radiation therapy or chemotherapy.This cancer is typically malignant in about 35 percent of cases.