The blood–thymus barrier regulates exchange of substances between the
circulatory system
The blood circulatory system is a system of organs that includes the heart, blood vessels, and blood which is circulated throughout the entire body of a human or other vertebrate. It includes the cardiovascular system, or vascular system, tha ...
and
thymus
The thymus is a specialized primary lymphoid organ of the immune system. Within the thymus, thymus cell lymphocytes or ''T cells'' mature. T cells are critical to the adaptive immune system, where the body adapts to specific foreign invaders. ...
, providing a sequestered environment for immature
T cells
A T cell is a type of lymphocyte. T cells are one of the important white blood cells of the immune system and play a central role in the adaptive immune response. T cells can be distinguished from other lymphocytes by the presence of a T-cell re ...
to develop. The barrier also prevents the immature T cells from contacting foreign
antigens (since contact with antigens at this stage will cause the T cells to die by
apoptosis).
The barrier is formed by the continuous blood capillaries in the thymic cortex, reinforced by type 1 epithelial reticular cells (sometimes called
thymic epithelial cell
Thymic epithelial cells (TECs) are specialized cells with high degree of anatomic, phenotypic and functional heterogeneity that are located in the outer layer (epithelium) of the thymic stroma. The thymus, as a primary lymphoid organ, mediates T c ...
s) and
macrophages
Macrophages (abbreviated as M φ, MΦ or MP) ( el, large eaters, from Greek ''μακρός'' (') = large, ''φαγεῖν'' (') = to eat) are a type of white blood cell of the immune system that engulfs and digests pathogens, such as cancer ce ...
.
The existence of this barrier was first proposed in 1961 and demonstrated to exist in mice in 1963.
See also
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References
{{DEFAULTSORT:Blood-thymus barrier
Thorax (human anatomy)
Organs (anatomy)