1) Endocrine 2) Hormone 3) Internal secretion 
(from the article `hormone`) ...of one type of white blood cells (lymphocytes) and a consequent likelihood of early death from infection. Preparations of thymus glands from ...
A hormone secreted by the thymus gland. Its primary function is to stimulate the production of T-lymphocytes, which are an important part of the immune system. Thymosin also plays a role in the development of B-lymphocytes to plasma cells to produce antibodies.
<biochemistry> Peptide (28 amino acids) that restores aspects of immune function in vivo and in vitro. Possibly a thymic hormone. ... (18 Nov 1997) ... 
(thi´mo-sin) a humoral factor secreted by the thymus; it promotes the maturation of T-lymphocytes.
Peptide (28 amino acids) that restores aspects of immune function in vivo and in vitro . Possibly a thymic hormone.
Type: Term Pronunciation: thī′mō-sin Definitions: 1. A polypeptide hormone that restores T-cell function in a thymectomized animal.
Thymosin: One of several polypeptide hormones secreted by the thymus that control the maturation of T cells. They are derived from a polypeptide called prothymosin-alpha (PTMA) or alpha thymosin.
[n] - hormone secreted by the thymus
thymosin A protein isolated from cell-free extracts of the thymus gland, having the cpacity to stimulate the development of immunologically competent lymphocytes.
noun hormone secreted by the thymus; stimulates immunological activity of lymphoid tissue